<!DOCTYPE html>
<!-- saved from url=(0029)chrome-error://chromewebdata/ -->
<html dir="ltr" lang="zh" i18n-processed=""><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

    <meta name="viewport" content="width=device-width, initial-scale=1.0,
                                 maximum-scale=1.0, user-scalable=no">
    <title>www.baidu.com</title>
    <style>/* Copyright 2017 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file. */

    a {
        color: rgb(88, 88, 88);
    }

    body {
        background-color: rgb(247, 247, 247);
        color: rgb(100, 100, 100);
    }

    #details-button {
        background: inherit;
        border: 0;
        float: none;
        margin: 0;
        padding: 10px 0;
        text-transform: uppercase;
    }

    .hidden {
        display: none;
    }

    html {
        -webkit-text-size-adjust: 100%;
        font-size: 125%;
    }

    .icon {
        background-repeat: no-repeat;
        background-size: 100%;
    }</style>
    <style>/* Copyright 2014 The Chromium Authors. All rights reserved.
   Use of this source code is governed by a BSD-style license that can be
   found in the LICENSE file. */

    button {
        border: 0;
        border-radius: 2px;
        box-sizing: border-box;
        color: #fff;
        cursor: pointer;
        float: right;
        font-size: .875em;
        margin: 0;
        padding: 10px 24px;
        transition: box-shadow 200ms cubic-bezier(0.4, 0, 0.2, 1);
        user-select: none;
    }

    [dir='rtl'] button {
        float: left;
    }

    .bad-clock button,
    .captive-portal button,
    .main-frame-blocked button,
    .neterror button,
    .offline button,
    .ssl button {
        background: rgb(66, 133, 244);
    }

    button:active {
        background: rgb(50, 102, 213);
        outline: 0;
    }

    button:hover {
        box-shadow: 0 1px 3px rgba(0, 0, 0, .50);
    }

    #debugging {
        display: inline;
        overflow: auto;
    }

    .debugging-content {
        line-height: 1em;
        margin-bottom: 0;
        margin-top: 1em;
    }

    .debugging-content-fixed-width {
        display: block;
        font-family: monospace;
        font-size: 1.2em;
        margin-top: 0.5em;
    }

    .debugging-title {
        font-weight: bold;
    }

    #details {
        color: #696969;
        margin: 0 0 50px;
    }

    #details p:not(:first-of-type) {
        margin-top: 20px;
    }

    #details-button:hover {
        box-shadow: inherit;
        text-decoration: underline;
    }

    .error-code {
        color: #646464;
        font-size: .86667em;
        text-transform: uppercase;
    }

    #error-debugging-info {
        font-size: 0.8em;
    }

    h1 {
        color: #333;
        font-size: 1.6em;
        font-weight: normal;
        line-height: 1.25em;
        margin-bottom: 16px;
    }

    h2 {
        font-size: 1.2em;
        font-weight: normal;
    }

    .icon {
        height: 72px;
        margin: 0 0 40px;
        width: 72px;
    }

    input[type=checkbox] {
        opacity: 0;
    }

    input[type=checkbox]:focus ~ .checkbox {
        outline: -webkit-focus-ring-color auto 5px;
    }

    .interstitial-wrapper {
        box-sizing: border-box;
        font-size: 1em;
        line-height: 1.6em;
        margin: 14vh auto 0;
        max-width: 600px;
        width: 100%;
    }

    #main-message > p {
        display: inline;
    }

    #extended-reporting-opt-in {
        font-size: .875em;
        margin-top: 39px;
    }

    #extended-reporting-opt-in label {
        position: relative;
        display: flex;
        align-items: flex-start;
    }

    .nav-wrapper {
        margin-top: 51px;
    }

    .nav-wrapper::after {
        clear: both;
        content: '';
        display: table;
        width: 100%;
    }

    .small-link {
        color: #696969;
        font-size: .875em;
    }

    .checkboxes {
        flex: 0 0 24px;
    }

    .checkbox {
        background: transparent;
        border: 1px solid white;
        border-radius: 2px;
        display: block;
        height: 14px;
        left: 0;
        position: absolute;
        right: 0;
        top: 3px;
        width: 14px;
    }

    .checkbox::before {
        background: transparent;
        border: 2px solid white;
        border-right-width: 0;
        border-top-width: 0;
        content: '';
        height: 4px;
        left: 2px;
        opacity: 0;
        position: absolute;
        top: 3px;
        transform: rotate(-45deg);
        width: 9px;
    }

    input[type=checkbox]:checked ~ .checkbox::before {
        opacity: 1;
    }

    @media (max-width: 700px) {
        .interstitial-wrapper {
            padding: 0 10%;
        }

        #error-debugging-info {
            overflow: auto;
        }
    }

    @media (max-height: 600px) {
        .error-code {
            margin-top: 10px;
        }
    }

    @media (max-width: 420px) {
        button,
        [dir='rtl'] button,
        .small-link {
            float: none;
            font-size: .825em;
            font-weight: 400;
            margin: 0;
            text-transform: uppercase;
            width: 100%;
        }

        #details {
            margin: 20px 0 20px 0;
        }

        #details p:not(:first-of-type) {
            margin-top: 10px;
        }

        #details-button {
            display: block;
            margin-top: 20px;
            text-align: center;
            width: 100%;
        }

        .interstitial-wrapper {
            padding: 0 5%;
        }

        #extended-reporting-opt-in {
            margin-top: 24px;
        }

        .nav-wrapper {
            margin-top: 30px;
        }
    }

    /**
 * Mobile specific styling.
 * Navigation buttons are anchored to the bottom of the screen.
 * Details message replaces the top content in its own scrollable area.
 */

    @media (max-width: 420px) {
        #details-button {
            border: 0;
            margin: 8px 0 0;
        }

        .secondary-button {
            -webkit-margin-end: 0;
            margin-top: 16px;
        }
    }

    /* Fixed nav. */
    @media (min-width: 240px) and (max-width: 420px) and
    (min-height: 401px),
    (min-width: 421px) and (min-height: 240px) and
    (max-height: 560px) {
        body .nav-wrapper {
            background: #f7f7f7;
            bottom: 0;
            box-shadow: 0 -22px 40px rgb(247, 247, 247);
            left: 0;
            margin: 0 auto;
            max-width: 736px;
            padding-left: 24px;
            padding-right: 24px;
            position: fixed;
            right: 0;
            width: 100%;
            z-index: 2;
        }

        .interstitial-wrapper {
            max-width: 736px;
        }

        #details,
        #main-content {
            padding-bottom: 40px;
        }

        #details {
            padding-top: 5.5vh;
        }

        #details-button:hover {
            box-shadow: none;
        }
    }

    @media (max-width: 420px) and (orientation: portrait),
    (max-height: 560px) {
        body {
            margin: 0 auto;
        }

        button,
        [dir='rtl'] button,
        button.small-link {
            font-family: Roboto-Regular,Helvetica;
            font-size: .933em;
            font-weight: 600;
            margin: 6px 0;
            text-transform: uppercase;
            transform: translatez(0);
        }

        .nav-wrapper {
            box-sizing: border-box;
            padding-bottom: 8px;
            width: 100%;
        }

        .error-code {
            margin-top: 0;
        }

        #details {
            box-sizing: border-box;
            height: auto;
            margin: 0;
            opacity: 1;
            transition: opacity 250ms cubic-bezier(0.4, 0, 0.2, 1);
        }

        #details.hidden,
        #main-content.hidden {
            display: block;
            height: 0;
            opacity: 0;
            overflow: hidden;
            padding-bottom: 0;
            transition: none;
        }

        #details-button {
            padding-bottom: 16px;
            padding-top: 16px;
        }

        h1 {
            font-size: 1.5em;
            margin-bottom: 8px;
        }

        .icon {
            margin-bottom: 5.69vh;
        }

        .interstitial-wrapper {
            box-sizing: border-box;
            margin: 7vh auto 12px;
            padding: 0 24px;
            position: relative;
        }

        .interstitial-wrapper p {
            font-size: .95em;
            line-height: 1.61em;
            margin-top: 8px;
        }

        #main-content {
            margin: 0;
            transition: opacity 100ms cubic-bezier(0.4, 0, 0.2, 1);
        }

        .small-link {
            border: 0;
        }

        .suggested-left > #control-buttons,
        .suggested-right > #control-buttons {
            float: none;
            margin: 0;
        }
    }

    @media (min-width: 421px) and (min-height: 500px) and (max-height: 560px) {
        .interstitial-wrapper {
            margin-top: 10vh;
        }
    }

    @media (min-height: 400px) and (orientation:portrait) {
        .interstitial-wrapper {
            margin-bottom: 145px;
        }
    }

    @media (min-height: 299px) {
        .nav-wrapper {
            padding-bottom: 16px;
        }
    }

    @media (min-height: 500px) and (max-height: 650px) and (max-width: 414px) and
    (orientation: portrait) {
        .interstitial-wrapper {
            margin-top: 7vh;
        }
    }

    @media (min-height: 650px) and (max-width: 414px) and (orientation: portrait) {
        .interstitial-wrapper {
            margin-top: 10vh;
        }
    }

    /* Small mobile screens. No fixed nav. */
    @media (max-height: 400px) and (orientation: portrait),
    (max-height: 239px) and (orientation: landscape),
    (max-width: 419px) and (max-height: 399px) {
        .interstitial-wrapper {
            display: flex;
            flex-direction: column;
            margin-bottom: 0;
        }

        #details {
            flex: 1 1 auto;
            order: 0;
        }

        #main-content {
            flex: 1 1 auto;
            order: 0;
        }

        .nav-wrapper {
            flex: 0 1 auto;
            margin-top: 8px;
            order: 1;
            padding-left: 0;
            padding-right: 0;
            position: relative;
            width: 100%;
        }
    }

    @media (max-width: 239px) and (orientation: portrait) {
        .nav-wrapper {
            padding-left: 0;
            padding-right: 0;
        }
    }
    </style>
    <style>/* Copyright 2013 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file. */

    /* Don't use the main frame div when the error is in a subframe. */
    html[subframe] #main-frame-error {
        display: none;
    }

    /* Don't use the subframe error div when the error is in a main frame. */
    html:not([subframe]) #sub-frame-error {
        display: none;
    }

    #diagnose-button {
        -webkit-margin-start: 0;
        float: none;
        margin-bottom: 10px;
        margin-top: 20px;
    }

    h1 {
        margin-top: 0;
        word-wrap: break-word;
    }

    h1 span {
        font-weight: 500;
    }

    h2 {
        color: #666;
        font-size: 1.2em;
        font-weight: normal;
        margin: 10px 0;
    }

    a {
        color: rgb(17, 85, 204);
        text-decoration: none;
    }

    .icon {
        -webkit-user-select: none;
        display: inline-block;
    }

    .icon-generic {
        /**
   * Can't access chrome://theme/IDR_ERROR_NETWORK_GENERIC from an untrusted
   * renderer process, so embed the resource manually.
   */
        content: -webkit-image-set(
                url() 1x,
                url() 2x);
    }

    .icon-offline {
        content: -webkit-image-set(
                url() 1x,
                url() 2x);
        position: relative;
    }

    .icon-disabled {
        content: -webkit-image-set(
                url() 1x,
                url() 2x);
        width: 112px;
    }

    .error-code {
        display: block;
        font-size: .8em;
    }

    #content-top {
        margin: 20px;
    }

    #help-box-inner {
        background-color: #f9f9f9;
        border-top: 1px solid #EEE;
        color: #444;
        padding: 20px;
        text-align: start;
    }

    .hidden {
        display: none;
    }

    #suggestion {
        margin-top: 15px;
    }

    #suggestions-list p {
        -webkit-margin-after: 0;
    }

    #suggestions-list ul {
        margin-top: 0;
    }

    .single-suggestion {
        list-style-type: none;
        padding-left: 0;
    }

    #short-suggestion {
        margin-top: 5px;
    }

    #sub-frame-error-details {

        color: #8F8F8F;

        /* Not done on mobile for performance reasons. */
        text-shadow: 0 1px 0 rgba(255,255,255,0.3);

    }

    [jscontent=hostName],
    [jscontent=failedUrl] {
        overflow-wrap: break-word;
    }

    #search-container {
        /* Prevents a space between controls. */
        display: flex;
        margin-top: 20px;
    }

    #search-box {
        border: 1px solid #cdcdcd;
        flex-grow: 1;
        font-size: 1em;
        height: 26px;
        margin-right: 0;
        padding: 1px 9px;
    }

    #search-box:focus {
        border: 1px solid rgb(93, 154, 255);
        outline: none;
    }

    #search-button {
        border: none;
        border-bottom-left-radius: 0;
        border-top-left-radius: 0;
        box-shadow: none;
        display: flex;
        height: 30px;
        margin: 0;
        padding: 0;
        width: 60px;
    }

    #search-image {
        content:
                -webkit-image-set(
                        url() 1x,
                        url() 2x);
        margin: auto;
    }

    .secondary-button {
        -webkit-margin-end: 16px;
        background: #d9d9d9;
        color: #696969;
    }

    .snackbar {
        background: #323232;
        border-radius: 2px;
        bottom: 24px;
        box-sizing: border-box;
        color: #fff;
        font-size: .87em;
        left: 24px;
        max-width: 568px;
        min-width: 288px;
        opacity: 0;
        padding: 16px 24px 12px;
        position: fixed;
        transform: translateY(90px);
        will-change: opacity, transform;
        z-index: 999;
    }

    .snackbar-show {
        -webkit-animation:
                show-snackbar .25s cubic-bezier(0.0, 0.0, 0.2, 1) forwards,
                hide-snackbar .25s cubic-bezier(0.4, 0.0, 1, 1) forwards 5s;
    }

    @-webkit-keyframes show-snackbar {
        100% {
            opacity: 1;
            transform: translateY(0);
        }
    }

    @-webkit-keyframes hide-snackbar {
        0% {
            opacity: 1;
            transform: translateY(0);
        }
        100% {
            opacity: 0;
            transform: translateY(90px);
        }
    }

    .suggestions {
        margin-top: 18px;
    }

    .suggestion-header {
        font-weight: bold;
        margin-bottom: 4px;
    }

    .suggestion-body {
        color: #777;
    }

    /* Increase line height at higher resolutions. */
    @media (min-width: 641px) and (min-height: 641px) {
        #help-box-inner {
            line-height: 18px;
        }
    }

    /* Decrease padding at low sizes. */
    @media (max-width: 640px), (max-height: 640px) {
        h1 {
            margin: 0 0 15px;
        }
        #content-top {
            margin: 15px;
        }
        #help-box-inner {
            padding: 20px;
        }
        .suggestions {
            margin-top: 10px;
        }
        .suggestion-header {
            margin-bottom: 0;
        }
    }

    /* Don't allow overflow when in a subframe. */
    html[subframe] body {
        overflow: hidden;
    }

    #sub-frame-error {
        -webkit-align-items: center;
        background-color: #DDD;
        display: -webkit-flex;
        -webkit-flex-flow: column;
        height: 100%;
        -webkit-justify-content: center;
        left: 0;
        position: absolute;
        text-align: center;
        top: 0;
        transition: background-color .2s ease-in-out;
        width: 100%;
    }

    #sub-frame-error:hover {
        background-color: #EEE;
    }

    #sub-frame-error .icon-generic {
        margin: 0 0 16px;
    }

    #sub-frame-error-details {
        margin: 0 10px;
        text-align: center;
        visibility: hidden;
    }

    /* Show details only when hovering. */
    #sub-frame-error:hover #sub-frame-error-details {
        visibility: visible;
    }

    /* If the iframe is too small, always hide the error code. */
    /* TODO(mmenke): See if overflow: no-display works better, once supported. */
    @media (max-width: 200px), (max-height: 95px) {
        #sub-frame-error-details {
            display: none;
        }
    }

    /* Adjust icon for small embedded frames in apps. */
    @media (max-height: 100px) {
        #sub-frame-error .icon-generic {
            height: auto;
            margin: 0;
            padding-top: 0;
            width: 25px;
        }
    }

    /* details-button is special; it's a <button> element that looks like a link. */
    #details-button {
        box-shadow: none;
        min-width: 0;
    }

    /* Styles for platform dependent separation of controls and details button. */
    .suggested-left > #control-buttons,
    .suggested-left #stale-load-button,
    .suggested-right > #details-button {
        float: left;
    }

    .suggested-right > #control-buttons,
    .suggested-right #stale-load-button,
    .suggested-left > #details-button {
        float: right;
    }

    .suggested-left .secondary-button {
        -webkit-margin-end: 0px;
        -webkit-margin-start: 16px;
    }

    #details-button.singular {
        float: none;
    }

    /* download-button shows both icon and text. */
    #download-button {
        box-shadow: none;
        position: relative;
    }

    #download-button:before {
        -webkit-margin-end: 4px;
        background: -webkit-image-set(
                url() 1x,
                url() 2x)
        no-repeat;
        content: '';
        display: inline-block;
        width: 24px;
        height: 24px;
        vertical-align: middle;
    }

    #download-button:disabled {
        background: rgb(180, 206, 249);
        color: rgb(255, 255, 255);
    }

    #buttons::after {
        clear: both;
        content: '';
        display: block;
        width: 100%;
    }

    /* Offline page */
    .offline {
        transition: -webkit-filter 1.5s cubic-bezier(0.65, 0.05, 0.36, 1),
        background-color 1.5s cubic-bezier(0.65, 0.05, 0.36, 1);
        will-change: -webkit-filter, background-color;
    }

    .offline #main-message > p {
        display: none;
    }

    .offline.inverted {
        -webkit-filter: invert(100%);
        background-color: #000;
    }

    .offline .interstitial-wrapper {
        color: #2b2b2b;
        font-size: 1em;
        line-height: 1.55;
        margin: 0 auto;
        max-width: 600px;
        padding-top: 100px;
        width: 100%;
    }

    .offline .runner-container {
        direction: ltr;
        height: 150px;
        max-width: 600px;
        overflow: hidden;
        position: absolute;
        top: 35px;
        width: 44px;
    }

    .offline .runner-canvas {
        height: 150px;
        max-width: 600px;
        opacity: 1;
        overflow: hidden;
        position: absolute;
        top: 0;
        z-index: 2;
    }

    .offline .controller {
        background: rgba(247,247,247, .1);
        height: 100vh;
        left: 0;
        position: absolute;
        top: 0;
        width: 100vw;
        z-index: 1;
    }

    #offline-resources {
        display: none;
    }

    @media (max-width: 420px) {
        .suggested-left > #control-buttons,
        .suggested-right > #control-buttons {
            float: none;
        }

        .snackbar {
            left: 0;
            bottom: 0;
            width: 100%;
            border-radius: 0;
        }
    }

    @media (max-height: 350px) {
        h1 {
            margin: 0 0 15px;
        }

        .icon-offline {
            margin: 0 0 10px;
        }

        .interstitial-wrapper {
            margin-top: 5%;
        }

        .nav-wrapper {
            margin-top: 30px;
        }
    }

    @media (min-width: 420px) and (max-width: 736px) and
    (min-height: 240px) and (max-height: 420px) and
    (orientation:landscape) {
        .interstitial-wrapper {
            margin-bottom: 100px;
        }
    }

    @media (max-width: 360px) and (max-height: 480px) {
        .offline .interstitial-wrapper {
            padding-top: 60px;
        }

        .offline .runner-container {
            top: 8px;
        }
    }

    @media (min-height: 240px) and (orientation: landscape) {
        .offline .interstitial-wrapper {
            margin-bottom: 90px;
        }

        .icon-offline {
            margin-bottom: 20px;
        }
    }

    @media (max-height: 320px) and (orientation: landscape) {
        .icon-offline {
            margin-bottom: 0;
        }

        .offline .runner-container {
            top: 10px;
        }
    }

    @media (max-width: 240px) {
        button {
            padding-left: 12px;
            padding-right: 12px;
        }

        .interstitial-wrapper {
            overflow: inherit;
            padding: 0 8px;
        }
    }

    @media (max-width: 120px) {
        button {
            width: auto;
        }
    }

    .arcade-mode,
    .arcade-mode .runner-container,
    .arcade-mode .runner-canvas {
        image-rendering: pixelated;
        max-width: 100%;
        overflow: hidden;
    }

    .arcade-mode #buttons,
    .arcade-mode #main-content {
        opacity: 0;
        overflow: hidden;
    }

    .arcade-mode .interstitial-wrapper {
        height: 100vh;
        max-width: 100%;
        overflow: hidden;
    }

    .arcade-mode .runner-container {
        left: 0;
        margin: auto;
        right: 0;
        transform-origin: top center;
        transition: transform 250ms cubic-bezier(0.4, 0.0, 1, 1) .4s;
        z-index: 2;
    }
    </style>
    <script>// Copyright 2017 The Chromium Authors. All rights reserved.
    // Use of this source code is governed by a BSD-style license that can be
    // found in the LICENSE file.

    // This is the shared code for security interstitials. It is used for both SSL
    // interstitials and Safe Browsing interstitials.

    // Should match security_interstitials::SecurityInterstitialCommand
    /** @enum| {string} */
    var SecurityInterstitialCommandId = {
        CMD_DONT_PROCEED: 0,
        CMD_PROCEED: 1,
        // Ways for user to get more information
        CMD_SHOW_MORE_SECTION: 2,
        CMD_OPEN_HELP_CENTER: 3,
        CMD_OPEN_DIAGNOSTIC: 4,
        // Primary button actions
        CMD_RELOAD: 5,
        CMD_OPEN_DATE_SETTINGS: 6,
        CMD_OPEN_LOGIN: 7,
        // Safe Browsing Extended Reporting
        CMD_DO_REPORT: 8,
        CMD_DONT_REPORT: 9,
        CMD_OPEN_REPORTING_PRIVACY: 10,
        CMD_OPEN_WHITEPAPER: 11,
        // Report a phishing error.
        CMD_REPORT_PHISHING_ERROR: 12
    };

    var HIDDEN_CLASS = 'hidden';

    /**
     * A convenience method for sending commands to the parent page.
     * @param {string} cmd  The command to send.
     */
    function sendCommand(cmd) {
        if (window.certificateErrorPageController) {
            switch (cmd) {
                case SecurityInterstitialCommandId.CMD_DONT_PROCEED:
                    certificateErrorPageController.dontProceed();
                    break;
                case SecurityInterstitialCommandId.CMD_PROCEED:
                    certificateErrorPageController.proceed();
                    break;
                case SecurityInterstitialCommandId.CMD_SHOW_MORE_SECTION:
                    certificateErrorPageController.showMoreSection();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_HELP_CENTER:
                    certificateErrorPageController.openHelpCenter();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_DIAGNOSTIC:
                    certificateErrorPageController.openDiagnostic();
                    break;
                case SecurityInterstitialCommandId.CMD_RELOAD:
                    certificateErrorPageController.reload();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_DATE_SETTINGS:
                    certificateErrorPageController.openDateSettings();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_LOGIN:
                    certificateErrorPageController.openLogin();
                    break;
                case SecurityInterstitialCommandId.CMD_DO_REPORT:
                    certificateErrorPageController.doReport();
                    break;
                case SecurityInterstitialCommandId.CMD_DONT_REPORT:
                    certificateErrorPageController.dontReport();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_REPORTING_PRIVACY:
                    certificateErrorPageController.openReportingPrivacy();
                    break;
                case SecurityInterstitialCommandId.CMD_OPEN_WHITEPAPER:
                    certificateErrorPageController.openWhitepaper();
                    break;
                case SecurityInterstitialCommandId.CMD_REPORT_PHISHING_ERROR:
                    certificateErrorPageController.reportPhishingError();
                    break;
            }
            return;
        }
//
        window.domAutomationController.send(cmd);
//
//
    }

    /**
     * Call this to stop clicks on <a href="#"> links from scrolling to the top of
     * the page (and possibly showing a # in the link).
     */
    function preventDefaultOnPoundLinkClicks() {
        document.addEventListener('click', function(e) {
            var anchor = findAncestor(/** @type {Node} */ (e.target), function(el) {
                return el.tagName == 'A';
            });
            // Use getAttribute() to prevent URL normalization.
            if (anchor && anchor.getAttribute('href') == '#')
                e.preventDefault();
        });
    }
    </script>
    <script>// Copyright 2015 The Chromium Authors. All rights reserved.
    // Use of this source code is governed by a BSD-style license that can be
    // found in the LICENSE file.

    var mobileNav = false;

    /**
     * For small screen mobile the navigation buttons are moved
     * below the advanced text.
     */
    function onResize() {
        var helpOuterBox = document.querySelector('#details');
        var mainContent = document.querySelector('#main-content');
        var mediaQuery = '(min-width: 240px) and (max-width: 420px) and ' +
            '(min-height: 401px), ' +
            '(max-height: 560px) and (min-height: 240px) and ' +
            '(min-width: 421px)';

        var detailsHidden = helpOuterBox.classList.contains(HIDDEN_CLASS);
        var runnerContainer = document.querySelector('.runner-container');

        // Check for change in nav status.
        if (mobileNav != window.matchMedia(mediaQuery).matches) {
            mobileNav = !mobileNav;

            // Handle showing the top content / details sections according to state.
            if (mobileNav) {
                mainContent.classList.toggle(HIDDEN_CLASS, !detailsHidden);
                helpOuterBox.classList.toggle(HIDDEN_CLASS, detailsHidden);
                if (runnerContainer) {
                    runnerContainer.classList.toggle(HIDDEN_CLASS, !detailsHidden);
                }
            } else if (!detailsHidden) {
                // Non mobile nav with visible details.
                mainContent.classList.remove(HIDDEN_CLASS);
                helpOuterBox.classList.remove(HIDDEN_CLASS);
                if (runnerContainer) {
                    runnerContainer.classList.remove(HIDDEN_CLASS);
                }
            }
        }
    }

    function setupMobileNav() {
        window.addEventListener('resize', onResize);
        onResize();
    }

    document.addEventListener('DOMContentLoaded', setupMobileNav);
    </script>
    <script>// Copyright 2013 The Chromium Authors. All rights reserved.
    // Use of this source code is governed by a BSD-style license that can be
    // found in the LICENSE file.

    function toggleHelpBox() {
        var helpBoxOuter = document.getElementById('details');
        helpBoxOuter.classList.toggle(HIDDEN_CLASS);
        var detailsButton = document.getElementById('details-button');
        if (helpBoxOuter.classList.contains(HIDDEN_CLASS))
            detailsButton.innerText = detailsButton.detailsText;
        else
            detailsButton.innerText = detailsButton.hideDetailsText;

        // Details appears over the main content on small screens.
        if (mobileNav) {
            document.getElementById('main-content').classList.toggle(HIDDEN_CLASS);
            var runnerContainer = document.querySelector('.runner-container');
            if (runnerContainer) {
                runnerContainer.classList.toggle(HIDDEN_CLASS);
            }
        }
    }

    function diagnoseErrors() {
//
        if (window.errorPageController)
            errorPageController.diagnoseErrorsButtonClick();
//
//
    }

    // Subframes use a different layout but the same html file.  This is to make it
    // easier to support platforms that load the error page via different
    // mechanisms (Currently just iOS).
    if (window.top.location != window.location)
        document.documentElement.setAttribute('subframe', '');

    // Re-renders the error page using |strings| as the dictionary of values.
    // Used by NetErrorTabHelper to update DNS error pages with probe results.
    function updateForDnsProbe(strings) {
        var context = new JsEvalContext(strings);
        jstProcess(context, document.getElementById('t'));
    }

    // Given the classList property of an element, adds an icon class to the list
    // and removes the previously-
    function updateIconClass(classList, newClass) {
        var oldClass;

        if (classList.hasOwnProperty('last_icon_class')) {
            oldClass = classList['last_icon_class'];
            if (oldClass == newClass)
                return;
        }

        classList.add(newClass);
        if (oldClass !== undefined)
            classList.remove(oldClass);

        classList['last_icon_class'] = newClass;

        if (newClass == 'icon-offline') {
            document.body.classList.add('offline');
            new Runner('.interstitial-wrapper');
        } else {
            document.body.classList.add('neterror');
        }
    }

    // Does a search using |baseSearchUrl| and the text in the search box.
    function search(baseSearchUrl) {
        var searchTextNode = document.getElementById('search-box');
        document.location = baseSearchUrl + searchTextNode.value;
        return false;
    }

    // Use to track clicks on elements generated by the navigation correction
    // service.  If |trackingId| is negative, the element does not come from the
    // correction service.
    function trackClick(trackingId) {
        // This can't be done with XHRs because XHRs are cancelled on navigation
        // start, and because these are cross-site requests.
        if (trackingId >= 0 && errorPageController)
            errorPageController.trackClick(trackingId);
    }

    // Called when an <a> tag generated by the navigation correction service is
    // clicked.  Separate function from trackClick so the resources don't have to
    // be updated if new data is added to jstdata.
    function linkClicked(jstdata) {
        trackClick(jstdata.trackingId);
    }

    // Implements button clicks.  This function is needed during the transition
    // between implementing these in trunk chromium and implementing them in
    // iOS.
    function reloadButtonClick(url) {
        if (window.errorPageController) {
            errorPageController.reloadButtonClick();
        } else {
            location = url;
        }
    }

    function showSavedCopyButtonClick() {
        if (window.errorPageController) {
            errorPageController.showSavedCopyButtonClick();
        }
    }

    function downloadButtonClick() {
        if (window.errorPageController) {
            errorPageController.downloadButtonClick();
            var downloadButton = document.getElementById('download-button');
            downloadButton.disabled = true;
            downloadButton.textContent = downloadButton.disabledText;
        }
    }

    function detailsButtonClick() {
        if (window.errorPageController)
            errorPageController.detailsButtonClick();
    }

    /**
     * Replace the reload button with the Google cached copy suggestion.
     */
    function setUpCachedButton(buttonStrings) {
        var reloadButton = document.getElementById('reload-button');

        reloadButton.textContent = buttonStrings.msg;
        var url = buttonStrings.cacheUrl;
        var trackingId = buttonStrings.trackingId;
        reloadButton.onclick = function(e) {
            e.preventDefault();
            trackClick(trackingId);
            if (window.errorPageController) {
                errorPageController.trackCachedCopyButtonClick();
            }
            location = url;
        };
        reloadButton.style.display = '';
        document.getElementById('control-buttons').hidden = false;
    }

    var primaryControlOnLeft = true;
    //

    function onDocumentLoad() {
        var controlButtonDiv = document.getElementById('control-buttons');
        var reloadButton = document.getElementById('reload-button');
        var detailsButton = document.getElementById('details-button');
        var showSavedCopyButton = document.getElementById('show-saved-copy-button');
        var downloadButton = document.getElementById('download-button');

        var reloadButtonVisible = loadTimeData.valueExists('reloadButton') &&
            loadTimeData.getValue('reloadButton').msg;
        var showSavedCopyButtonVisible =
            loadTimeData.valueExists('showSavedCopyButton') &&
            loadTimeData.getValue('showSavedCopyButton').msg;
        var downloadButtonVisible =
            loadTimeData.valueExists('downloadButton') &&
            loadTimeData.getValue('downloadButton').msg;

        var primaryButton, secondaryButton;
        if (showSavedCopyButton.primary) {
            primaryButton = showSavedCopyButton;
            secondaryButton = reloadButton;
        } else {
            primaryButton = reloadButton;
            secondaryButton = showSavedCopyButton;
        }

        // Sets up the proper button layout for the current platform.
        if (primaryControlOnLeft) {
            buttons.classList.add('suggested-left');
            controlButtonDiv.insertBefore(secondaryButton, primaryButton);
        } else {
            buttons.classList.add('suggested-right');
            controlButtonDiv.insertBefore(primaryButton, secondaryButton);
        }

        // Check for Google cached copy suggestion.
        if (loadTimeData.valueExists('cacheButton')) {
            setUpCachedButton(loadTimeData.getValue('cacheButton'));
        }

        if (reloadButton.style.display == 'none' &&
            showSavedCopyButton.style.display == 'none' &&
            downloadButton.style.display == 'none') {
            detailsButton.classList.add('singular');
        }

        // Show control buttons.
        if (reloadButtonVisible || showSavedCopyButtonVisible ||
            downloadButtonVisible) {
            controlButtonDiv.hidden = false;

            // Set the secondary button state in the cases of two call to actions.
            if ((reloadButtonVisible || downloadButtonVisible) &&
                showSavedCopyButtonVisible) {
                secondaryButton.classList.add('secondary-button');
            }
        }
    }

    document.addEventListener('DOMContentLoaded', onDocumentLoad);
    </script>
    <script>// Copyright (c) 2014 The Chromium Authors. All rights reserved.
    // Use of this source code is governed by a BSD-style license that can be
    // found in the LICENSE file.
    (function() {
        'use strict';
        /**
         * T-Rex runner.
         * @param {string} outerContainerId Outer containing element id.
         * @param {Object} opt_config
         * @constructor
         * @export
         */
        function Runner(outerContainerId, opt_config) {
            // Singleton
            if (Runner.instance_) {
                return Runner.instance_;
            }
            Runner.instance_ = this;

            this.outerContainerEl = document.querySelector(outerContainerId);
            this.containerEl = null;
            this.snackbarEl = null;

            this.config = opt_config || Runner.config;
            // Logical dimensions of the container.
            this.dimensions = Runner.defaultDimensions;

            this.canvas = null;
            this.canvasCtx = null;

            this.tRex = null;

            this.distanceMeter = null;
            this.distanceRan = 0;

            this.highestScore = 0;

            this.time = 0;
            this.runningTime = 0;
            this.msPerFrame = 1000 / FPS;
            this.currentSpeed = this.config.SPEED;

            this.obstacles = [];

            this.activated = false; // Whether the easter egg has been activated.
            this.playing = false; // Whether the game is currently in play state.
            this.crashed = false;
            this.paused = false;
            this.inverted = false;
            this.invertTimer = 0;
            this.resizeTimerId_ = null;

            this.playCount = 0;

            // Sound FX.
            this.audioBuffer = null;
            this.soundFx = {};

            // Global web audio context for playing sounds.
            this.audioContext = null;

            // Images.
            this.images = {};
            this.imagesLoaded = 0;

            if (this.isDisabled()) {
                this.setupDisabledRunner();
            } else {
                this.loadImages();
            }
        }
        window['Runner'] = Runner;


        /**
         * Default game width.
         * @const
         */
        var DEFAULT_WIDTH = 600;

        /**
         * Frames per second.
         * @const
         */
        var FPS = 60;

        /** @const */
        var IS_HIDPI = window.devicePixelRatio > 1;

        /** @const */
        var IS_IOS = /iPad|iPhone|iPod/.test(window.navigator.platform);

        /** @const */
        var IS_MOBILE = /Android/.test(window.navigator.userAgent) || IS_IOS;

        /** @const */
        var IS_TOUCH_ENABLED = 'ontouchstart' in window;

        /** @const */
        var ARCADE_MODE_URL = 'chrome://dino/';

        /**
         * Default game configuration.
         * @enum {number}
         */
        Runner.config = {
            ACCELERATION: 0.001,
            BG_CLOUD_SPEED: 0.2,
            BOTTOM_PAD: 10,
            CLEAR_TIME: 3000,
            CLOUD_FREQUENCY: 0.5,
            GAMEOVER_CLEAR_TIME: 750,
            GAP_COEFFICIENT: 0.6,
            GRAVITY: 0.6,
            INITIAL_JUMP_VELOCITY: 12,
            INVERT_FADE_DURATION: 12000,
            INVERT_DISTANCE: 700,
            MAX_BLINK_COUNT: 3,
            MAX_CLOUDS: 6,
            MAX_OBSTACLE_LENGTH: 3,
            MAX_OBSTACLE_DUPLICATION: 2,
            MAX_SPEED: 13,
            MIN_JUMP_HEIGHT: 35,
            MOBILE_SPEED_COEFFICIENT: 1.2,
            RESOURCE_TEMPLATE_ID: 'audio-resources',
            SPEED: 6,
            SPEED_DROP_COEFFICIENT: 3,
            ARCADE_MODE_INITIAL_TOP_POSITION: 35,
            ARCADE_MODE_TOP_POSITION_PERCENT: 0.1
        };


        /**
         * Default dimensions.
         * @enum {string}
         */
        Runner.defaultDimensions = {
            WIDTH: DEFAULT_WIDTH,
            HEIGHT: 150
        };


        /**
         * CSS class names.
         * @enum {string}
         */
        Runner.classes = {
            ARCADE_MODE: 'arcade-mode',
            CANVAS: 'runner-canvas',
            CONTAINER: 'runner-container',
            CRASHED: 'crashed',
            ICON: 'icon-offline',
            INVERTED: 'inverted',
            SNACKBAR: 'snackbar',
            SNACKBAR_SHOW: 'snackbar-show',
            TOUCH_CONTROLLER: 'controller'
        };


        /**
         * Sprite definition layout of the spritesheet.
         * @enum {Object}
         */
        Runner.spriteDefinition = {
            LDPI: {
                CACTUS_LARGE: {x: 332, y: 2},
                CACTUS_SMALL: {x: 228, y: 2},
                CLOUD: {x: 86, y: 2},
                HORIZON: {x: 2, y: 54},
                MOON: {x: 484, y: 2},
                PTERODACTYL: {x: 134, y: 2},
                RESTART: {x: 2, y: 2},
                TEXT_SPRITE: {x: 655, y: 2},
                TREX: {x: 848, y: 2},
                STAR: {x: 645, y: 2}
            },
            HDPI: {
                CACTUS_LARGE: {x: 652, y: 2},
                CACTUS_SMALL: {x: 446, y: 2},
                CLOUD: {x: 166, y: 2},
                HORIZON: {x: 2, y: 104},
                MOON: {x: 954, y: 2},
                PTERODACTYL: {x: 260, y: 2},
                RESTART: {x: 2, y: 2},
                TEXT_SPRITE: {x: 1294, y: 2},
                TREX: {x: 1678, y: 2},
                STAR: {x: 1276, y: 2}
            }
        };


        /**
         * Sound FX. Reference to the ID of the audio tag on interstitial page.
         * @enum {string}
         */
        Runner.sounds = {
            BUTTON_PRESS: 'offline-sound-press',
            HIT: 'offline-sound-hit',
            SCORE: 'offline-sound-reached'
        };


        /**
         * Key code mapping.
         * @enum {Object}
         */
        Runner.keycodes = {
            JUMP: {'38': 1, '32': 1},  // Up, spacebar
            DUCK: {'40': 1},  // Down
            RESTART: {'13': 1}  // Enter
        };


        /**
         * Runner event names.
         * @enum {string}
         */
        Runner.events = {
            ANIM_END: 'webkitAnimationEnd',
            CLICK: 'click',
            KEYDOWN: 'keydown',
            KEYUP: 'keyup',
            MOUSEDOWN: 'mousedown',
            MOUSEUP: 'mouseup',
            RESIZE: 'resize',
            TOUCHEND: 'touchend',
            TOUCHSTART: 'touchstart',
            VISIBILITY: 'visibilitychange',
            BLUR: 'blur',
            FOCUS: 'focus',
            LOAD: 'load'
        };

        Runner.prototype = {
            /**
             * Whether the easter egg has been disabled. CrOS enterprise enrolled devices.
             * @return {boolean}
             */
            isDisabled: function() {
                return loadTimeData && loadTimeData.valueExists('disabledEasterEgg');
            },

            /**
             * For disabled instances, set up a snackbar with the disabled message.
             */
            setupDisabledRunner: function() {
                this.containerEl = document.createElement('div');
                this.containerEl.className = Runner.classes.SNACKBAR;
                this.containerEl.textContent = loadTimeData.getValue('disabledEasterEgg');
                this.outerContainerEl.appendChild(this.containerEl);

                // Show notification when the activation key is pressed.
                document.addEventListener(Runner.events.KEYDOWN, function(e) {
                    if (Runner.keycodes.JUMP[e.keyCode]) {
                        this.containerEl.classList.add(Runner.classes.SNACKBAR_SHOW);
                        document.querySelector('.icon').classList.add('icon-disabled');
                    }
                }.bind(this));
            },

            /**
             * Setting individual settings for debugging.
             * @param {string} setting
             * @param {*} value
             */
            updateConfigSetting: function(setting, value) {
                if (setting in this.config && value != undefined) {
                    this.config[setting] = value;

                    switch (setting) {
                        case 'GRAVITY':
                        case 'MIN_JUMP_HEIGHT':
                        case 'SPEED_DROP_COEFFICIENT':
                            this.tRex.config[setting] = value;
                            break;
                        case 'INITIAL_JUMP_VELOCITY':
                            this.tRex.setJumpVelocity(value);
                            break;
                        case 'SPEED':
                            this.setSpeed(value);
                            break;
                    }
                }
            },

            /**
             * Cache the appropriate image sprite from the page and get the sprite sheet
             * definition.
             */
            loadImages: function() {
                if (IS_HIDPI) {
                    Runner.imageSprite = document.getElementById('offline-resources-2x');
                    this.spriteDef = Runner.spriteDefinition.HDPI;
                } else {
                    Runner.imageSprite = document.getElementById('offline-resources-1x');
                    this.spriteDef = Runner.spriteDefinition.LDPI;
                }

                if (Runner.imageSprite.complete) {
                    this.init();
                } else {
                    // If the images are not yet loaded, add a listener.
                    Runner.imageSprite.addEventListener(Runner.events.LOAD,
                        this.init.bind(this));
                }
            },

            /**
             * Load and decode base 64 encoded sounds.
             */
            loadSounds: function() {
                if (!IS_IOS) {
                    this.audioContext = new AudioContext();

                    var resourceTemplate =
                        document.getElementById(this.config.RESOURCE_TEMPLATE_ID).content;

                    for (var sound in Runner.sounds) {
                        var soundSrc =
                            resourceTemplate.getElementById(Runner.sounds[sound]).src;
                        soundSrc = soundSrc.substr(soundSrc.indexOf(',') + 1);
                        var buffer = decodeBase64ToArrayBuffer(soundSrc);

                        // Async, so no guarantee of order in array.
                        this.audioContext.decodeAudioData(buffer, function(index, audioData) {
                            this.soundFx[index] = audioData;
                        }.bind(this, sound));
                    }
                }
            },

            /**
             * Sets the game speed. Adjust the speed accordingly if on a smaller screen.
             * @param {number} opt_speed
             */
            setSpeed: function(opt_speed) {
                var speed = opt_speed || this.currentSpeed;

                // Reduce the speed on smaller mobile screens.
                if (this.dimensions.WIDTH < DEFAULT_WIDTH) {
                    var mobileSpeed = speed * this.dimensions.WIDTH / DEFAULT_WIDTH *
                        this.config.MOBILE_SPEED_COEFFICIENT;
                    this.currentSpeed = mobileSpeed > speed ? speed : mobileSpeed;
                } else if (opt_speed) {
                    this.currentSpeed = opt_speed;
                }
            },

            /**
             * Game initialiser.
             */
            init: function() {
                // Hide the static icon.
                document.querySelector('.' + Runner.classes.ICON).style.visibility =
                    'hidden';

                this.adjustDimensions();
                this.setSpeed();

                this.containerEl = document.createElement('div');
                this.containerEl.className = Runner.classes.CONTAINER;

                // Player canvas container.
                this.canvas = createCanvas(this.containerEl, this.dimensions.WIDTH,
                    this.dimensions.HEIGHT, Runner.classes.PLAYER);

                this.canvasCtx = this.canvas.getContext('2d');
                this.canvasCtx.fillStyle = '#f7f7f7';
                this.canvasCtx.fill();
                Runner.updateCanvasScaling(this.canvas);

                // Horizon contains clouds, obstacles and the ground.
                this.horizon = new Horizon(this.canvas, this.spriteDef, this.dimensions,
                    this.config.GAP_COEFFICIENT);

                // Distance meter
                this.distanceMeter = new DistanceMeter(this.canvas,
                    this.spriteDef.TEXT_SPRITE, this.dimensions.WIDTH);

                // Draw t-rex
                this.tRex = new Trex(this.canvas, this.spriteDef.TREX);

                this.outerContainerEl.appendChild(this.containerEl);

                if (IS_MOBILE) {
                    this.createTouchController();
                }

                this.startListening();
                this.update();

                window.addEventListener(Runner.events.RESIZE,
                    this.debounceResize.bind(this));
            },

            /**
             * Create the touch controller. A div that covers whole screen.
             */
            createTouchController: function() {
                this.touchController = document.createElement('div');
                this.touchController.className = Runner.classes.TOUCH_CONTROLLER;
            },

            /**
             * Debounce the resize event.
             */
            debounceResize: function() {
                if (!this.resizeTimerId_) {
                    this.resizeTimerId_ =
                        setInterval(this.adjustDimensions.bind(this), 250);
                }
            },

            /**
             * Adjust game space dimensions on resize.
             */
            adjustDimensions: function() {
                clearInterval(this.resizeTimerId_);
                this.resizeTimerId_ = null;

                var boxStyles = window.getComputedStyle(this.outerContainerEl);
                var padding = Number(boxStyles.paddingLeft.substr(0,
                    boxStyles.paddingLeft.length - 2));

                this.dimensions.WIDTH = this.outerContainerEl.offsetWidth - padding * 2;
                if (this.isArcadeMode()) {
                    this.dimensions.WIDTH = Math.min(DEFAULT_WIDTH, this.dimensions.WIDTH);
                    if (this.activated) {
                        this.setArcadeModeContainerScale();
                    }
                }

                // Redraw the elements back onto the canvas.
                if (this.canvas) {
                    this.canvas.width = this.dimensions.WIDTH;
                    this.canvas.height = this.dimensions.HEIGHT;

                    Runner.updateCanvasScaling(this.canvas);

                    this.distanceMeter.calcXPos(this.dimensions.WIDTH);
                    this.clearCanvas();
                    this.horizon.update(0, 0, true);
                    this.tRex.update(0);

                    // Outer container and distance meter.
                    if (this.playing || this.crashed || this.paused) {
                        this.containerEl.style.width = this.dimensions.WIDTH + 'px';
                        this.containerEl.style.height = this.dimensions.HEIGHT + 'px';
                        this.distanceMeter.update(0, Math.ceil(this.distanceRan));
                        this.stop();
                    } else {
                        this.tRex.draw(0, 0);
                    }

                    // Game over panel.
                    if (this.crashed && this.gameOverPanel) {
                        this.gameOverPanel.updateDimensions(this.dimensions.WIDTH);
                        this.gameOverPanel.draw();
                    }
                }
            },

            /**
             * Play the game intro.
             * Canvas container width expands out to the full width.
             */
            playIntro: function() {
                if (!this.activated && !this.crashed) {
                    this.playingIntro = true;
                    this.tRex.playingIntro = true;

                    // CSS animation definition.
                    var keyframes = '@-webkit-keyframes intro { ' +
                        'from { width:' + Trex.config.WIDTH + 'px }' +
                        'to { width: ' + this.dimensions.WIDTH + 'px }' +
                        '}';
                    document.styleSheets[0].insertRule(keyframes, 0);

                    this.containerEl.addEventListener(Runner.events.ANIM_END,
                        this.startGame.bind(this));

                    this.containerEl.style.webkitAnimation = 'intro .4s ease-out 1 both';
                    this.containerEl.style.width = this.dimensions.WIDTH + 'px';

                    if (this.touchController) {
                        this.outerContainerEl.appendChild(this.touchController);
                    }
                    this.playing = true;
                    this.activated = true;
                } else if (this.crashed) {
                    this.restart();
                }
            },


            /**
             * Update the game status to started.
             */
            startGame: function() {
                if (this.isArcadeMode()) {
                    this.setArcadeMode();
                }
                this.runningTime = 0;
                this.playingIntro = false;
                this.tRex.playingIntro = false;
                this.containerEl.style.webkitAnimation = '';
                this.playCount++;

                // Handle tabbing off the page. Pause the current game.
                document.addEventListener(Runner.events.VISIBILITY,
                    this.onVisibilityChange.bind(this));

                window.addEventListener(Runner.events.BLUR,
                    this.onVisibilityChange.bind(this));

                window.addEventListener(Runner.events.FOCUS,
                    this.onVisibilityChange.bind(this));
            },

            clearCanvas: function() {
                this.canvasCtx.clearRect(0, 0, this.dimensions.WIDTH,
                    this.dimensions.HEIGHT);
            },

            /**
             * Update the game frame and schedules the next one.
             */
            update: function() {
                this.updatePending = false;

                var now = getTimeStamp();
                var deltaTime = now - (this.time || now);
                this.time = now;

                if (this.playing) {
                    this.clearCanvas();

                    if (this.tRex.jumping) {
                        this.tRex.updateJump(deltaTime);
                    }

                    this.runningTime += deltaTime;
                    var hasObstacles = this.runningTime > this.config.CLEAR_TIME;

                    // First jump triggers the intro.
                    if (this.tRex.jumpCount == 1 && !this.playingIntro) {
                        this.playIntro();
                    }

                    // The horizon doesn't move until the intro is over.
                    if (this.playingIntro) {
                        this.horizon.update(0, this.currentSpeed, hasObstacles);
                    } else {
                        deltaTime = !this.activated ? 0 : deltaTime;
                        this.horizon.update(deltaTime, this.currentSpeed, hasObstacles,
                            this.inverted);
                    }

                    // Check for collisions.
                    var collision = hasObstacles &&
                        checkForCollision(this.horizon.obstacles[0], this.tRex);

                    if (!collision) {
                        this.distanceRan += this.currentSpeed * deltaTime / this.msPerFrame;

                        if (this.currentSpeed < this.config.MAX_SPEED) {
                            this.currentSpeed += this.config.ACCELERATION;
                        }
                    } else {
                        this.gameOver();
                    }

                    var playAchievementSound = this.distanceMeter.update(deltaTime,
                        Math.ceil(this.distanceRan));

                    if (playAchievementSound) {
                        this.playSound(this.soundFx.SCORE);
                    }

                    // Night mode.
                    if (this.invertTimer > this.config.INVERT_FADE_DURATION) {
                        this.invertTimer = 0;
                        this.invertTrigger = false;
                        this.invert();
                    } else if (this.invertTimer) {
                        this.invertTimer += deltaTime;
                    } else {
                        var actualDistance =
                            this.distanceMeter.getActualDistance(Math.ceil(this.distanceRan));

                        if (actualDistance > 0) {
                            this.invertTrigger = !(actualDistance %
                                this.config.INVERT_DISTANCE);

                            if (this.invertTrigger && this.invertTimer === 0) {
                                this.invertTimer += deltaTime;
                                this.invert();
                            }
                        }
                    }
                }

                if (this.playing || (!this.activated &&
                        this.tRex.blinkCount < Runner.config.MAX_BLINK_COUNT)) {
                    this.tRex.update(deltaTime);
                    this.scheduleNextUpdate();
                }
            },

            /**
             * Event handler.
             */
            handleEvent: function(e) {
                return (function(evtType, events) {
                    switch (evtType) {
                        case events.KEYDOWN:
                        case events.TOUCHSTART:
                        case events.MOUSEDOWN:
                            this.onKeyDown(e);
                            break;
                        case events.KEYUP:
                        case events.TOUCHEND:
                        case events.MOUSEUP:
                            this.onKeyUp(e);
                            break;
                    }
                }.bind(this))(e.type, Runner.events);
            },

            /**
             * Bind relevant key / mouse / touch listeners.
             */
            startListening: function() {
                // Keys.
                document.addEventListener(Runner.events.KEYDOWN, this);
                document.addEventListener(Runner.events.KEYUP, this);

                if (IS_MOBILE) {
                    // Mobile only touch devices.
                    this.touchController.addEventListener(Runner.events.TOUCHSTART, this);
                    this.touchController.addEventListener(Runner.events.TOUCHEND, this);
                    this.containerEl.addEventListener(Runner.events.TOUCHSTART, this);
                } else {
                    // Mouse.
                    document.addEventListener(Runner.events.MOUSEDOWN, this);
                    document.addEventListener(Runner.events.MOUSEUP, this);
                }
            },

            /**
             * Remove all listeners.
             */
            stopListening: function() {
                document.removeEventListener(Runner.events.KEYDOWN, this);
                document.removeEventListener(Runner.events.KEYUP, this);

                if (IS_MOBILE) {
                    this.touchController.removeEventListener(Runner.events.TOUCHSTART, this);
                    this.touchController.removeEventListener(Runner.events.TOUCHEND, this);
                    this.containerEl.removeEventListener(Runner.events.TOUCHSTART, this);
                } else {
                    document.removeEventListener(Runner.events.MOUSEDOWN, this);
                    document.removeEventListener(Runner.events.MOUSEUP, this);
                }
            },

            /**
             * Process keydown.
             * @param {Event} e
             */
            onKeyDown: function(e) {
                // Prevent native page scrolling whilst tapping on mobile.
                if (IS_MOBILE && this.playing) {
                    e.preventDefault();
                }

                if (!this.crashed && !this.paused) {
                    if (Runner.keycodes.JUMP[e.keyCode] ||
                        e.type == Runner.events.TOUCHSTART) {
                        e.preventDefault();
                        // Starting the game for the first time.
                        if (!this.playing) {
                            this.loadSounds();
                            this.playing = true;
                            this.update();
                            if (window.errorPageController) {
                                errorPageController.trackEasterEgg();
                            }
                        }
                        // Start jump.
                        if (!this.tRex.jumping && !this.tRex.ducking) {
                            this.playSound(this.soundFx.BUTTON_PRESS);
                            this.tRex.startJump(this.currentSpeed);
                        }
                    } else if (this.playing && Runner.keycodes.DUCK[e.keyCode]) {
                        e.preventDefault();
                        if (this.tRex.jumping) {
                            // Speed drop, activated only when jump key is not pressed.
                            this.tRex.setSpeedDrop();
                        } else if (!this.tRex.jumping && !this.tRex.ducking) {
                            // Duck.
                            this.tRex.setDuck(true);
                        }
                    }
                } else if (this.crashed && e.type == Runner.events.TOUCHSTART &&
                    e.currentTarget == this.containerEl) {
                    this.restart();
                }
            },


            /**
             * Process key up.
             * @param {Event} e
             */
            onKeyUp: function(e) {
                var keyCode = String(e.keyCode);
                var isjumpKey = Runner.keycodes.JUMP[keyCode] ||
                    e.type == Runner.events.TOUCHEND ||
                    e.type == Runner.events.MOUSEDOWN;

                if (this.isRunning() && isjumpKey) {
                    this.tRex.endJump();
                } else if (Runner.keycodes.DUCK[keyCode]) {
                    this.tRex.speedDrop = false;
                    this.tRex.setDuck(false);
                } else if (this.crashed) {
                    // Check that enough time has elapsed before allowing jump key to restart.
                    var deltaTime = getTimeStamp() - this.time;

                    if (Runner.keycodes.RESTART[keyCode] || this.isLeftClickOnCanvas(e) ||
                        (deltaTime >= this.config.GAMEOVER_CLEAR_TIME &&
                            Runner.keycodes.JUMP[keyCode])) {
                        this.restart();
                    }
                } else if (this.paused && isjumpKey) {
                    // Reset the jump state
                    this.tRex.reset();
                    this.play();
                }
            },

            /**
             * Returns whether the event was a left click on canvas.
             * On Windows right click is registered as a click.
             * @param {Event} e
             * @return {boolean}
             */
            isLeftClickOnCanvas: function(e) {
                return e.button != null && e.button < 2 &&
                    e.type == Runner.events.MOUSEUP && e.target == this.canvas;
            },

            /**
             * RequestAnimationFrame wrapper.
             */
            scheduleNextUpdate: function() {
                if (!this.updatePending) {
                    this.updatePending = true;
                    this.raqId = requestAnimationFrame(this.update.bind(this));
                }
            },

            /**
             * Whether the game is running.
             * @return {boolean}
             */
            isRunning: function() {
                return !!this.raqId;
            },

            /**
             * Game over state.
             */
            gameOver: function() {
                this.playSound(this.soundFx.HIT);
                vibrate(200);

                this.stop();
                this.crashed = true;
                this.distanceMeter.achievement = false;

                this.tRex.update(100, Trex.status.CRASHED);

                // Game over panel.
                if (!this.gameOverPanel) {
                    this.gameOverPanel = new GameOverPanel(this.canvas,
                        this.spriteDef.TEXT_SPRITE, this.spriteDef.RESTART,
                        this.dimensions);
                } else {
                    this.gameOverPanel.draw();
                }

                // Update the high score.
                if (this.distanceRan > this.highestScore) {
                    this.highestScore = Math.ceil(this.distanceRan);
                    this.distanceMeter.setHighScore(this.highestScore);
                }

                // Reset the time clock.
                this.time = getTimeStamp();
            },

            stop: function() {
                this.playing = false;
                this.paused = true;
                cancelAnimationFrame(this.raqId);
                this.raqId = 0;
            },

            play: function() {
                if (!this.crashed) {
                    this.playing = true;
                    this.paused = false;
                    this.tRex.update(0, Trex.status.RUNNING);
                    this.time = getTimeStamp();
                    this.update();
                }
            },

            restart: function() {
                if (!this.raqId) {
                    this.playCount++;
                    this.runningTime = 0;
                    this.playing = true;
                    this.paused = false;
                    this.crashed = false;
                    this.distanceRan = 0;
                    this.setSpeed(this.config.SPEED);
                    this.time = getTimeStamp();
                    this.containerEl.classList.remove(Runner.classes.CRASHED);
                    this.clearCanvas();
                    this.distanceMeter.reset(this.highestScore);
                    this.horizon.reset();
                    this.tRex.reset();
                    this.playSound(this.soundFx.BUTTON_PRESS);
                    this.invert(true);
                    this.update();
                }
            },

            /**
             * Whether the game should go into arcade mode.
             * @return {boolean}
             */
            isArcadeMode: function() {
                return document.title == ARCADE_MODE_URL;
            },

            /**
             * Hides offline messaging for a fullscreen game only experience.
             */
            setArcadeMode: function() {
                document.body.classList.add(Runner.classes.ARCADE_MODE);
                this.setArcadeModeContainerScale();
            },

            /**
             * Sets the scaling for arcade mode.
             */
            setArcadeModeContainerScale: function() {
                var windowHeight = window.innerHeight;
                var scaleHeight = windowHeight / this.dimensions.HEIGHT;
                var scaleWidth = window.innerWidth / this.dimensions.WIDTH;
                var scale = Math.max(1, Math.min(scaleHeight, scaleWidth));
                var scaledCanvasHeight = this.dimensions.HEIGHT * scale;
                // Positions the game container at 10% of the available vertical window
                // height minus the game container height.
                var translateY = Math.ceil(Math.max(0, (windowHeight - scaledCanvasHeight -
                    Runner.config.ARCADE_MODE_INITIAL_TOP_POSITION) *
                    Runner.config.ARCADE_MODE_TOP_POSITION_PERCENT)) *
                    window.devicePixelRatio;
                this.containerEl.style.transform = 'scale(' + scale + ') translateY(' +
                    translateY + 'px)';
            },

            /**
             * Pause the game if the tab is not in focus.
             */
            onVisibilityChange: function(e) {
                if (document.hidden || document.webkitHidden || e.type == 'blur' ||
                    document.visibilityState != 'visible') {
                    this.stop();
                } else if (!this.crashed) {
                    this.tRex.reset();
                    this.play();
                }
            },

            /**
             * Play a sound.
             * @param {SoundBuffer} soundBuffer
             */
            playSound: function(soundBuffer) {
                if (soundBuffer) {
                    var sourceNode = this.audioContext.createBufferSource();
                    sourceNode.buffer = soundBuffer;
                    sourceNode.connect(this.audioContext.destination);
                    sourceNode.start(0);
                }
            },

            /**
             * Inverts the current page / canvas colors.
             * @param {boolean} Whether to reset colors.
             */
            invert: function(reset) {
                if (reset) {
                    document.body.classList.toggle(Runner.classes.INVERTED, false);
                    this.invertTimer = 0;
                    this.inverted = false;
                } else {
                    this.inverted = document.body.classList.toggle(Runner.classes.INVERTED,
                        this.invertTrigger);
                }
            }
        };


        /**
         * Updates the canvas size taking into
         * account the backing store pixel ratio and
         * the device pixel ratio.
         *
         * See article by Paul Lewis:
         * http://www.html5rocks.com/en/tutorials/canvas/hidpi/
         *
         * @param {HTMLCanvasElement} canvas
         * @param {number} opt_width
         * @param {number} opt_height
         * @return {boolean} Whether the canvas was scaled.
         */
        Runner.updateCanvasScaling = function(canvas, opt_width, opt_height) {
            var context = canvas.getContext('2d');

            // Query the various pixel ratios
            var devicePixelRatio = Math.floor(window.devicePixelRatio) || 1;
            var backingStoreRatio = Math.floor(context.webkitBackingStorePixelRatio) || 1;
            var ratio = devicePixelRatio / backingStoreRatio;

            // Upscale the canvas if the two ratios don't match
            if (devicePixelRatio !== backingStoreRatio) {
                var oldWidth = opt_width || canvas.width;
                var oldHeight = opt_height || canvas.height;

                canvas.width = oldWidth * ratio;
                canvas.height = oldHeight * ratio;

                canvas.style.width = oldWidth + 'px';
                canvas.style.height = oldHeight + 'px';

                // Scale the context to counter the fact that we've manually scaled
                // our canvas element.
                context.scale(ratio, ratio);
                return true;
            } else if (devicePixelRatio == 1) {
                // Reset the canvas width / height. Fixes scaling bug when the page is
                // zoomed and the devicePixelRatio changes accordingly.
                canvas.style.width = canvas.width + 'px';
                canvas.style.height = canvas.height + 'px';
            }
            return false;
        };


        /**
         * Get random number.
         * @param {number} min
         * @param {number} max
         * @param {number}
         */
        function getRandomNum(min, max) {
            return Math.floor(Math.random() * (max - min + 1)) + min;
        }


        /**
         * Vibrate on mobile devices.
         * @param {number} duration Duration of the vibration in milliseconds.
         */
        function vibrate(duration) {
            if (IS_MOBILE && window.navigator.vibrate) {
                window.navigator.vibrate(duration);
            }
        }


        /**
         * Create canvas element.
         * @param {HTMLElement} container Element to append canvas to.
         * @param {number} width
         * @param {number} height
         * @param {string} opt_classname
         * @return {HTMLCanvasElement}
         */
        function createCanvas(container, width, height, opt_classname) {
            var canvas = document.createElement('canvas');
            canvas.className = opt_classname ? Runner.classes.CANVAS + ' ' +
                opt_classname : Runner.classes.CANVAS;
            canvas.width = width;
            canvas.height = height;
            container.appendChild(canvas);

            return canvas;
        }


        /**
         * Decodes the base 64 audio to ArrayBuffer used by Web Audio.
         * @param {string} base64String
         */
        function decodeBase64ToArrayBuffer(base64String) {
            var len = (base64String.length / 4) * 3;
            var str = atob(base64String);
            var arrayBuffer = new ArrayBuffer(len);
            var bytes = new Uint8Array(arrayBuffer);

            for (var i = 0; i < len; i++) {
                bytes[i] = str.charCodeAt(i);
            }
            return bytes.buffer;
        }


        /**
         * Return the current timestamp.
         * @return {number}
         */
        function getTimeStamp() {
            return IS_IOS ? new Date().getTime() : performance.now();
        }


//******************************************************************************


        /**
         * Game over panel.
         * @param {!HTMLCanvasElement} canvas
         * @param {Object} textImgPos
         * @param {Object} restartImgPos
         * @param {!Object} dimensions Canvas dimensions.
         * @constructor
         */
        function GameOverPanel(canvas, textImgPos, restartImgPos, dimensions) {
            this.canvas = canvas;
            this.canvasCtx = canvas.getContext('2d');
            this.canvasDimensions = dimensions;
            this.textImgPos = textImgPos;
            this.restartImgPos = restartImgPos;
            this.draw();
        };


        /**
         * Dimensions used in the panel.
         * @enum {number}
         */
        GameOverPanel.dimensions = {
            TEXT_X: 0,
            TEXT_Y: 13,
            TEXT_WIDTH: 191,
            TEXT_HEIGHT: 11,
            RESTART_WIDTH: 36,
            RESTART_HEIGHT: 32
        };


        GameOverPanel.prototype = {
            /**
             * Update the panel dimensions.
             * @param {number} width New canvas width.
             * @param {number} opt_height Optional new canvas height.
             */
            updateDimensions: function(width, opt_height) {
                this.canvasDimensions.WIDTH = width;
                if (opt_height) {
                    this.canvasDimensions.HEIGHT = opt_height;
                }
            },

            /**
             * Draw the panel.
             */
            draw: function() {
                var dimensions = GameOverPanel.dimensions;

                var centerX = this.canvasDimensions.WIDTH / 2;

                // Game over text.
                var textSourceX = dimensions.TEXT_X;
                var textSourceY = dimensions.TEXT_Y;
                var textSourceWidth = dimensions.TEXT_WIDTH;
                var textSourceHeight = dimensions.TEXT_HEIGHT;

                var textTargetX = Math.round(centerX - (dimensions.TEXT_WIDTH / 2));
                var textTargetY = Math.round((this.canvasDimensions.HEIGHT - 25) / 3);
                var textTargetWidth = dimensions.TEXT_WIDTH;
                var textTargetHeight = dimensions.TEXT_HEIGHT;

                var restartSourceWidth = dimensions.RESTART_WIDTH;
                var restartSourceHeight = dimensions.RESTART_HEIGHT;
                var restartTargetX = centerX - (dimensions.RESTART_WIDTH / 2);
                var restartTargetY = this.canvasDimensions.HEIGHT / 2;

                if (IS_HIDPI) {
                    textSourceY *= 2;
                    textSourceX *= 2;
                    textSourceWidth *= 2;
                    textSourceHeight *= 2;
                    restartSourceWidth *= 2;
                    restartSourceHeight *= 2;
                }

                textSourceX += this.textImgPos.x;
                textSourceY += this.textImgPos.y;

                // Game over text from sprite.
                this.canvasCtx.drawImage(Runner.imageSprite,
                    textSourceX, textSourceY, textSourceWidth, textSourceHeight,
                    textTargetX, textTargetY, textTargetWidth, textTargetHeight);

                // Restart button.
                this.canvasCtx.drawImage(Runner.imageSprite,
                    this.restartImgPos.x, this.restartImgPos.y,
                    restartSourceWidth, restartSourceHeight,
                    restartTargetX, restartTargetY, dimensions.RESTART_WIDTH,
                    dimensions.RESTART_HEIGHT);
            }
        };


//******************************************************************************

        /**
         * Check for a collision.
         * @param {!Obstacle} obstacle
         * @param {!Trex} tRex T-rex object.
         * @param {HTMLCanvasContext} opt_canvasCtx Optional canvas context for drawing
         *    collision boxes.
         * @return {Array<CollisionBox>}
         */
        function checkForCollision(obstacle, tRex, opt_canvasCtx) {
            var obstacleBoxXPos = Runner.defaultDimensions.WIDTH + obstacle.xPos;

            // Adjustments are made to the bounding box as there is a 1 pixel white
            // border around the t-rex and obstacles.
            var tRexBox = new CollisionBox(
                tRex.xPos + 1,
                tRex.yPos + 1,
                tRex.config.WIDTH - 2,
                tRex.config.HEIGHT - 2);

            var obstacleBox = new CollisionBox(
                obstacle.xPos + 1,
                obstacle.yPos + 1,
                obstacle.typeConfig.width * obstacle.size - 2,
                obstacle.typeConfig.height - 2);

            // Debug outer box
            if (opt_canvasCtx) {
                drawCollisionBoxes(opt_canvasCtx, tRexBox, obstacleBox);
            }

            // Simple outer bounds check.
            if (boxCompare(tRexBox, obstacleBox)) {
                var collisionBoxes = obstacle.collisionBoxes;
                var tRexCollisionBoxes = tRex.ducking ?
                    Trex.collisionBoxes.DUCKING : Trex.collisionBoxes.RUNNING;

                // Detailed axis aligned box check.
                for (var t = 0; t < tRexCollisionBoxes.length; t++) {
                    for (var i = 0; i < collisionBoxes.length; i++) {
                        // Adjust the box to actual positions.
                        var adjTrexBox =
                            createAdjustedCollisionBox(tRexCollisionBoxes[t], tRexBox);
                        var adjObstacleBox =
                            createAdjustedCollisionBox(collisionBoxes[i], obstacleBox);
                        var crashed = boxCompare(adjTrexBox, adjObstacleBox);

                        // Draw boxes for debug.
                        if (opt_canvasCtx) {
                            drawCollisionBoxes(opt_canvasCtx, adjTrexBox, adjObstacleBox);
                        }

                        if (crashed) {
                            return [adjTrexBox, adjObstacleBox];
                        }
                    }
                }
            }
            return false;
        };


        /**
         * Adjust the collision box.
         * @param {!CollisionBox} box The original box.
         * @param {!CollisionBox} adjustment Adjustment box.
         * @return {CollisionBox} The adjusted collision box object.
         */
        function createAdjustedCollisionBox(box, adjustment) {
            return new CollisionBox(
                box.x + adjustment.x,
                box.y + adjustment.y,
                box.width,
                box.height);
        };


        /**
         * Draw the collision boxes for debug.
         */
        function drawCollisionBoxes(canvasCtx, tRexBox, obstacleBox) {
            canvasCtx.save();
            canvasCtx.strokeStyle = '#f00';
            canvasCtx.strokeRect(tRexBox.x, tRexBox.y, tRexBox.width, tRexBox.height);

            canvasCtx.strokeStyle = '#0f0';
            canvasCtx.strokeRect(obstacleBox.x, obstacleBox.y,
                obstacleBox.width, obstacleBox.height);
            canvasCtx.restore();
        };


        /**
         * Compare two collision boxes for a collision.
         * @param {CollisionBox} tRexBox
         * @param {CollisionBox} obstacleBox
         * @return {boolean} Whether the boxes intersected.
         */
        function boxCompare(tRexBox, obstacleBox) {
            var crashed = false;
            var tRexBoxX = tRexBox.x;
            var tRexBoxY = tRexBox.y;

            var obstacleBoxX = obstacleBox.x;
            var obstacleBoxY = obstacleBox.y;

            // Axis-Aligned Bounding Box method.
            if (tRexBox.x < obstacleBoxX + obstacleBox.width &&
                tRexBox.x + tRexBox.width > obstacleBoxX &&
                tRexBox.y < obstacleBox.y + obstacleBox.height &&
                tRexBox.height + tRexBox.y > obstacleBox.y) {
                crashed = true;
            }

            return crashed;
        };


//******************************************************************************

        /**
         * Collision box object.
         * @param {number} x X position.
         * @param {number} y Y Position.
         * @param {number} w Width.
         * @param {number} h Height.
         */
        function CollisionBox(x, y, w, h) {
            this.x = x;
            this.y = y;
            this.width = w;
            this.height = h;
        };


//******************************************************************************

        /**
         * Obstacle.
         * @param {HTMLCanvasCtx} canvasCtx
         * @param {Obstacle.type} type
         * @param {Object} spritePos Obstacle position in sprite.
         * @param {Object} dimensions
         * @param {number} gapCoefficient Mutipler in determining the gap.
         * @param {number} speed
         * @param {number} opt_xOffset
         */
        function Obstacle(canvasCtx, type, spriteImgPos, dimensions,
                          gapCoefficient, speed, opt_xOffset) {

            this.canvasCtx = canvasCtx;
            this.spritePos = spriteImgPos;
            this.typeConfig = type;
            this.gapCoefficient = gapCoefficient;
            this.size = getRandomNum(1, Obstacle.MAX_OBSTACLE_LENGTH);
            this.dimensions = dimensions;
            this.remove = false;
            this.xPos = dimensions.WIDTH + (opt_xOffset || 0);
            this.yPos = 0;
            this.width = 0;
            this.collisionBoxes = [];
            this.gap = 0;
            this.speedOffset = 0;

            // For animated obstacles.
            this.currentFrame = 0;
            this.timer = 0;

            this.init(speed);
        };

        /**
         * Coefficient for calculating the maximum gap.
         * @const
         */
        Obstacle.MAX_GAP_COEFFICIENT = 1.5;

        /**
         * Maximum obstacle grouping count.
         * @const
         */
        Obstacle.MAX_OBSTACLE_LENGTH = 3,


            Obstacle.prototype = {
                /**
                 * Initialise the DOM for the obstacle.
                 * @param {number} speed
                 */
                init: function(speed) {
                    this.cloneCollisionBoxes();

                    // Only allow sizing if we're at the right speed.
                    if (this.size > 1 && this.typeConfig.multipleSpeed > speed) {
                        this.size = 1;
                    }

                    this.width = this.typeConfig.width * this.size;

                    // Check if obstacle can be positioned at various heights.
                    if (Array.isArray(this.typeConfig.yPos))  {
                        var yPosConfig = IS_MOBILE ? this.typeConfig.yPosMobile :
                            this.typeConfig.yPos;
                        this.yPos = yPosConfig[getRandomNum(0, yPosConfig.length - 1)];
                    } else {
                        this.yPos = this.typeConfig.yPos;
                    }

                    this.draw();

                    // Make collision box adjustments,
                    // Central box is adjusted to the size as one box.
                    //      ____        ______        ________
                    //    _|   |-|    _|     |-|    _|       |-|
                    //   | |<->| |   | |<--->| |   | |<----->| |
                    //   | | 1 | |   | |  2  | |   | |   3   | |
                    //   |_|___|_|   |_|_____|_|   |_|_______|_|
                    //
                    if (this.size > 1) {
                        this.collisionBoxes[1].width = this.width - this.collisionBoxes[0].width -
                            this.collisionBoxes[2].width;
                        this.collisionBoxes[2].x = this.width - this.collisionBoxes[2].width;
                    }

                    // For obstacles that go at a different speed from the horizon.
                    if (this.typeConfig.speedOffset) {
                        this.speedOffset = Math.random() > 0.5 ? this.typeConfig.speedOffset :
                            -this.typeConfig.speedOffset;
                    }

                    this.gap = this.getGap(this.gapCoefficient, speed);
                },

                /**
                 * Draw and crop based on size.
                 */
                draw: function() {
                    var sourceWidth = this.typeConfig.width;
                    var sourceHeight = this.typeConfig.height;

                    if (IS_HIDPI) {
                        sourceWidth = sourceWidth * 2;
                        sourceHeight = sourceHeight * 2;
                    }

                    // X position in sprite.
                    var sourceX = (sourceWidth * this.size) * (0.5 * (this.size - 1)) +
                        this.spritePos.x;

                    // Animation frames.
                    if (this.currentFrame > 0) {
                        sourceX += sourceWidth * this.currentFrame;
                    }

                    this.canvasCtx.drawImage(Runner.imageSprite,
                        sourceX, this.spritePos.y,
                        sourceWidth * this.size, sourceHeight,
                        this.xPos, this.yPos,
                        this.typeConfig.width * this.size, this.typeConfig.height);
                },

                /**
                 * Obstacle frame update.
                 * @param {number} deltaTime
                 * @param {number} speed
                 */
                update: function(deltaTime, speed) {
                    if (!this.remove) {
                        if (this.typeConfig.speedOffset) {
                            speed += this.speedOffset;
                        }
                        this.xPos -= Math.floor((speed * FPS / 1000) * deltaTime);

                        // Update frame
                        if (this.typeConfig.numFrames) {
                            this.timer += deltaTime;
                            if (this.timer >= this.typeConfig.frameRate) {
                                this.currentFrame =
                                    this.currentFrame == this.typeConfig.numFrames - 1 ?
                                        0 : this.currentFrame + 1;
                                this.timer = 0;
                            }
                        }
                        this.draw();

                        if (!this.isVisible()) {
                            this.remove = true;
                        }
                    }
                },

                /**
                 * Calculate a random gap size.
                 * - Minimum gap gets wider as speed increses
                 * @param {number} gapCoefficient
                 * @param {number} speed
                 * @return {number} The gap size.
                 */
                getGap: function(gapCoefficient, speed) {
                    var minGap = Math.round(this.width * speed +
                        this.typeConfig.minGap * gapCoefficient);
                    var maxGap = Math.round(minGap * Obstacle.MAX_GAP_COEFFICIENT);
                    return getRandomNum(minGap, maxGap);
                },

                /**
                 * Check if obstacle is visible.
                 * @return {boolean} Whether the obstacle is in the game area.
                 */
                isVisible: function() {
                    return this.xPos + this.width > 0;
                },

                /**
                 * Make a copy of the collision boxes, since these will change based on
                 * obstacle type and size.
                 */
                cloneCollisionBoxes: function() {
                    var collisionBoxes = this.typeConfig.collisionBoxes;

                    for (var i = collisionBoxes.length - 1; i >= 0; i--) {
                        this.collisionBoxes[i] = new CollisionBox(collisionBoxes[i].x,
                            collisionBoxes[i].y, collisionBoxes[i].width,
                            collisionBoxes[i].height);
                    }
                }
            };


        /**
         * Obstacle definitions.
         * minGap: minimum pixel space betweeen obstacles.
         * multipleSpeed: Speed at which multiples are allowed.
         * speedOffset: speed faster / slower than the horizon.
         * minSpeed: Minimum speed which the obstacle can make an appearance.
         */
        Obstacle.types = [
            {
                type: 'CACTUS_SMALL',
                width: 17,
                height: 35,
                yPos: 105,
                multipleSpeed: 4,
                minGap: 120,
                minSpeed: 0,
                collisionBoxes: [
                    new CollisionBox(0, 7, 5, 27),
                    new CollisionBox(4, 0, 6, 34),
                    new CollisionBox(10, 4, 7, 14)
                ]
            },
            {
                type: 'CACTUS_LARGE',
                width: 25,
                height: 50,
                yPos: 90,
                multipleSpeed: 7,
                minGap: 120,
                minSpeed: 0,
                collisionBoxes: [
                    new CollisionBox(0, 12, 7, 38),
                    new CollisionBox(8, 0, 7, 49),
                    new CollisionBox(13, 10, 10, 38)
                ]
            },
            {
                type: 'PTERODACTYL',
                width: 46,
                height: 40,
                yPos: [ 100, 75, 50 ], // Variable height.
                yPosMobile: [ 100, 50 ], // Variable height mobile.
                multipleSpeed: 999,
                minSpeed: 8.5,
                minGap: 150,
                collisionBoxes: [
                    new CollisionBox(15, 15, 16, 5),
                    new CollisionBox(18, 21, 24, 6),
                    new CollisionBox(2, 14, 4, 3),
                    new CollisionBox(6, 10, 4, 7),
                    new CollisionBox(10, 8, 6, 9)
                ],
                numFrames: 2,
                frameRate: 1000/6,
                speedOffset: .8
            }
        ];


//******************************************************************************
        /**
         * T-rex game character.
         * @param {HTMLCanvas} canvas
         * @param {Object} spritePos Positioning within image sprite.
         * @constructor
         */
        function Trex(canvas, spritePos) {
            this.canvas = canvas;
            this.canvasCtx = canvas.getContext('2d');
            this.spritePos = spritePos;
            this.xPos = 0;
            this.yPos = 0;
            // Position when on the ground.
            this.groundYPos = 0;
            this.currentFrame = 0;
            this.currentAnimFrames = [];
            this.blinkDelay = 0;
            this.blinkCount = 0;
            this.animStartTime = 0;
            this.timer = 0;
            this.msPerFrame = 1000 / FPS;
            this.config = Trex.config;
            // Current status.
            this.status = Trex.status.WAITING;

            this.jumping = false;
            this.ducking = false;
            this.jumpVelocity = 0;
            this.reachedMinHeight = false;
            this.speedDrop = false;
            this.jumpCount = 0;
            this.jumpspotX = 0;

            this.init();
        };


        /**
         * T-rex player config.
         * @enum {number}
         */
        Trex.config = {
            DROP_VELOCITY: -5,
            GRAVITY: 0.6,
            HEIGHT: 47,
            HEIGHT_DUCK: 25,
            INIITAL_JUMP_VELOCITY: -10,
            INTRO_DURATION: 1500,
            MAX_JUMP_HEIGHT: 30,
            MIN_JUMP_HEIGHT: 30,
            SPEED_DROP_COEFFICIENT: 3,
            SPRITE_WIDTH: 262,
            START_X_POS: 50,
            WIDTH: 44,
            WIDTH_DUCK: 59
        };


        /**
         * Used in collision detection.
         * @type {Array<CollisionBox>}
         */
        Trex.collisionBoxes = {
            DUCKING: [
                new CollisionBox(1, 18, 55, 25)
            ],
            RUNNING: [
                new CollisionBox(22, 0, 17, 16),
                new CollisionBox(1, 18, 30, 9),
                new CollisionBox(10, 35, 14, 8),
                new CollisionBox(1, 24, 29, 5),
                new CollisionBox(5, 30, 21, 4),
                new CollisionBox(9, 34, 15, 4)
            ]
        };


        /**
         * Animation states.
         * @enum {string}
         */
        Trex.status = {
            CRASHED: 'CRASHED',
            DUCKING: 'DUCKING',
            JUMPING: 'JUMPING',
            RUNNING: 'RUNNING',
            WAITING: 'WAITING'
        };

        /**
         * Blinking coefficient.
         * @const
         */
        Trex.BLINK_TIMING = 7000;


        /**
         * Animation config for different states.
         * @enum {Object}
         */
        Trex.animFrames = {
            WAITING: {
                frames: [44, 0],
                msPerFrame: 1000 / 3
            },
            RUNNING: {
                frames: [88, 132],
                msPerFrame: 1000 / 12
            },
            CRASHED: {
                frames: [220],
                msPerFrame: 1000 / 60
            },
            JUMPING: {
                frames: [0],
                msPerFrame: 1000 / 60
            },
            DUCKING: {
                frames: [262, 321],
                msPerFrame: 1000 / 8
            }
        };


        Trex.prototype = {
            /**
             * T-rex player initaliser.
             * Sets the t-rex to blink at random intervals.
             */
            init: function() {
                this.groundYPos = Runner.defaultDimensions.HEIGHT - this.config.HEIGHT -
                    Runner.config.BOTTOM_PAD;
                this.yPos = this.groundYPos;
                this.minJumpHeight = this.groundYPos - this.config.MIN_JUMP_HEIGHT;

                this.draw(0, 0);
                this.update(0, Trex.status.WAITING);
            },

            /**
             * Setter for the jump velocity.
             * The approriate drop velocity is also set.
             */
            setJumpVelocity: function(setting) {
                this.config.INIITAL_JUMP_VELOCITY = -setting;
                this.config.DROP_VELOCITY = -setting / 2;
            },

            /**
             * Set the animation status.
             * @param {!number} deltaTime
             * @param {Trex.status} status Optional status to switch to.
             */
            update: function(deltaTime, opt_status) {
                this.timer += deltaTime;

                // Update the status.
                if (opt_status) {
                    this.status = opt_status;
                    this.currentFrame = 0;
                    this.msPerFrame = Trex.animFrames[opt_status].msPerFrame;
                    this.currentAnimFrames = Trex.animFrames[opt_status].frames;

                    if (opt_status == Trex.status.WAITING) {
                        this.animStartTime = getTimeStamp();
                        this.setBlinkDelay();
                    }
                }

                // Game intro animation, T-rex moves in from the left.
                if (this.playingIntro && this.xPos < this.config.START_X_POS) {
                    this.xPos += Math.round((this.config.START_X_POS /
                        this.config.INTRO_DURATION) * deltaTime);
                }

                if (this.status == Trex.status.WAITING) {
                    this.blink(getTimeStamp());
                } else {
                    this.draw(this.currentAnimFrames[this.currentFrame], 0);
                }

                // Update the frame position.
                if (this.timer >= this.msPerFrame) {
                    this.currentFrame = this.currentFrame ==
                    this.currentAnimFrames.length - 1 ? 0 : this.currentFrame + 1;
                    this.timer = 0;
                }

                // Speed drop becomes duck if the down key is still being pressed.
                if (this.speedDrop && this.yPos == this.groundYPos) {
                    this.speedDrop = false;
                    this.setDuck(true);
                }
            },

            /**
             * Draw the t-rex to a particular position.
             * @param {number} x
             * @param {number} y
             */
            draw: function(x, y) {
                var sourceX = x;
                var sourceY = y;
                var sourceWidth = this.ducking && this.status != Trex.status.CRASHED ?
                    this.config.WIDTH_DUCK : this.config.WIDTH;
                var sourceHeight = this.config.HEIGHT;

                if (IS_HIDPI) {
                    sourceX *= 2;
                    sourceY *= 2;
                    sourceWidth *= 2;
                    sourceHeight *= 2;
                }

                // Adjustments for sprite sheet position.
                sourceX += this.spritePos.x;
                sourceY += this.spritePos.y;

                // Ducking.
                if (this.ducking && this.status != Trex.status.CRASHED) {
                    this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
                        sourceWidth, sourceHeight,
                        this.xPos, this.yPos,
                        this.config.WIDTH_DUCK, this.config.HEIGHT);
                } else {
                    // Crashed whilst ducking. Trex is standing up so needs adjustment.
                    if (this.ducking && this.status == Trex.status.CRASHED) {
                        this.xPos++;
                    }
                    // Standing / running
                    this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
                        sourceWidth, sourceHeight,
                        this.xPos, this.yPos,
                        this.config.WIDTH, this.config.HEIGHT);
                }
            },

            /**
             * Sets a random time for the blink to happen.
             */
            setBlinkDelay: function() {
                this.blinkDelay = Math.ceil(Math.random() * Trex.BLINK_TIMING);
            },

            /**
             * Make t-rex blink at random intervals.
             * @param {number} time Current time in milliseconds.
             */
            blink: function(time) {
                var deltaTime = time - this.animStartTime;

                if (deltaTime >= this.blinkDelay) {
                    this.draw(this.currentAnimFrames[this.currentFrame], 0);

                    if (this.currentFrame == 1) {
                        // Set new random delay to blink.
                        this.setBlinkDelay();
                        this.animStartTime = time;
                        this.blinkCount++;
                    }
                }
            },

            /**
             * Initialise a jump.
             * @param {number} speed
             */
            startJump: function(speed) {
                if (!this.jumping) {
                    this.update(0, Trex.status.JUMPING);
                    // Tweak the jump velocity based on the speed.
                    this.jumpVelocity = this.config.INIITAL_JUMP_VELOCITY - (speed / 10);
                    this.jumping = true;
                    this.reachedMinHeight = false;
                    this.speedDrop = false;
                }
            },

            /**
             * Jump is complete, falling down.
             */
            endJump: function() {
                if (this.reachedMinHeight &&
                    this.jumpVelocity < this.config.DROP_VELOCITY) {
                    this.jumpVelocity = this.config.DROP_VELOCITY;
                }
            },

            /**
             * Update frame for a jump.
             * @param {number} deltaTime
             * @param {number} speed
             */
            updateJump: function(deltaTime, speed) {
                var msPerFrame = Trex.animFrames[this.status].msPerFrame;
                var framesElapsed = deltaTime / msPerFrame;

                // Speed drop makes Trex fall faster.
                if (this.speedDrop) {
                    this.yPos += Math.round(this.jumpVelocity *
                        this.config.SPEED_DROP_COEFFICIENT * framesElapsed);
                } else {
                    this.yPos += Math.round(this.jumpVelocity * framesElapsed);
                }

                this.jumpVelocity += this.config.GRAVITY * framesElapsed;

                // Minimum height has been reached.
                if (this.yPos < this.minJumpHeight || this.speedDrop) {
                    this.reachedMinHeight = true;
                }

                // Reached max height
                if (this.yPos < this.config.MAX_JUMP_HEIGHT || this.speedDrop) {
                    this.endJump();
                }

                // Back down at ground level. Jump completed.
                if (this.yPos > this.groundYPos) {
                    this.reset();
                    this.jumpCount++;
                }

                this.update(deltaTime);
            },

            /**
             * Set the speed drop. Immediately cancels the current jump.
             */
            setSpeedDrop: function() {
                this.speedDrop = true;
                this.jumpVelocity = 1;
            },

            /**
             * @param {boolean} isDucking.
             */
            setDuck: function(isDucking) {
                if (isDucking && this.status != Trex.status.DUCKING) {
                    this.update(0, Trex.status.DUCKING);
                    this.ducking = true;
                } else if (this.status == Trex.status.DUCKING) {
                    this.update(0, Trex.status.RUNNING);
                    this.ducking = false;
                }
            },

            /**
             * Reset the t-rex to running at start of game.
             */
            reset: function() {
                this.yPos = this.groundYPos;
                this.jumpVelocity = 0;
                this.jumping = false;
                this.ducking = false;
                this.update(0, Trex.status.RUNNING);
                this.midair = false;
                this.speedDrop = false;
                this.jumpCount = 0;
            }
        };


//******************************************************************************

        /**
         * Handles displaying the distance meter.
         * @param {!HTMLCanvasElement} canvas
         * @param {Object} spritePos Image position in sprite.
         * @param {number} canvasWidth
         * @constructor
         */
        function DistanceMeter(canvas, spritePos, canvasWidth) {
            this.canvas = canvas;
            this.canvasCtx = canvas.getContext('2d');
            this.image = Runner.imageSprite;
            this.spritePos = spritePos;
            this.x = 0;
            this.y = 5;

            this.currentDistance = 0;
            this.maxScore = 0;
            this.highScore = 0;
            this.container = null;

            this.digits = [];
            this.achievement = false;
            this.defaultString = '';
            this.flashTimer = 0;
            this.flashIterations = 0;
            this.invertTrigger = false;

            this.config = DistanceMeter.config;
            this.maxScoreUnits = this.config.MAX_DISTANCE_UNITS;
            this.init(canvasWidth);
        };


        /**
         * @enum {number}
         */
        DistanceMeter.dimensions = {
            WIDTH: 10,
            HEIGHT: 13,
            DEST_WIDTH: 11
        };


        /**
         * Y positioning of the digits in the sprite sheet.
         * X position is always 0.
         * @type {Array<number>}
         */
        DistanceMeter.yPos = [0, 13, 27, 40, 53, 67, 80, 93, 107, 120];


        /**
         * Distance meter config.
         * @enum {number}
         */
        DistanceMeter.config = {
            // Number of digits.
            MAX_DISTANCE_UNITS: 5,

            // Distance that causes achievement animation.
            ACHIEVEMENT_DISTANCE: 100,

            // Used for conversion from pixel distance to a scaled unit.
            COEFFICIENT: 0.025,

            // Flash duration in milliseconds.
            FLASH_DURATION: 1000 / 4,

            // Flash iterations for achievement animation.
            FLASH_ITERATIONS: 3
        };


        DistanceMeter.prototype = {
            /**
             * Initialise the distance meter to '00000'.
             * @param {number} width Canvas width in px.
             */
            init: function(width) {
                var maxDistanceStr = '';

                this.calcXPos(width);
                this.maxScore = this.maxScoreUnits;
                for (var i = 0; i < this.maxScoreUnits; i++) {
                    this.draw(i, 0);
                    this.defaultString += '0';
                    maxDistanceStr += '9';
                }

                this.maxScore = parseInt(maxDistanceStr);
            },

            /**
             * Calculate the xPos in the canvas.
             * @param {number} canvasWidth
             */
            calcXPos: function(canvasWidth) {
                this.x = canvasWidth - (DistanceMeter.dimensions.DEST_WIDTH *
                    (this.maxScoreUnits + 1));
            },

            /**
             * Draw a digit to canvas.
             * @param {number} digitPos Position of the digit.
             * @param {number} value Digit value 0-9.
             * @param {boolean} opt_highScore Whether drawing the high score.
             */
            draw: function(digitPos, value, opt_highScore) {
                var sourceWidth = DistanceMeter.dimensions.WIDTH;
                var sourceHeight = DistanceMeter.dimensions.HEIGHT;
                var sourceX = DistanceMeter.dimensions.WIDTH * value;
                var sourceY = 0;

                var targetX = digitPos * DistanceMeter.dimensions.DEST_WIDTH;
                var targetY = this.y;
                var targetWidth = DistanceMeter.dimensions.WIDTH;
                var targetHeight = DistanceMeter.dimensions.HEIGHT;

                // For high DPI we 2x source values.
                if (IS_HIDPI) {
                    sourceWidth *= 2;
                    sourceHeight *= 2;
                    sourceX *= 2;
                }

                sourceX += this.spritePos.x;
                sourceY += this.spritePos.y;

                this.canvasCtx.save();

                if (opt_highScore) {
                    // Left of the current score.
                    var highScoreX = this.x - (this.maxScoreUnits * 2) *
                        DistanceMeter.dimensions.WIDTH;
                    this.canvasCtx.translate(highScoreX, this.y);
                } else {
                    this.canvasCtx.translate(this.x, this.y);
                }

                this.canvasCtx.drawImage(this.image, sourceX, sourceY,
                    sourceWidth, sourceHeight,
                    targetX, targetY,
                    targetWidth, targetHeight
                );

                this.canvasCtx.restore();
            },

            /**
             * Covert pixel distance to a 'real' distance.
             * @param {number} distance Pixel distance ran.
             * @return {number} The 'real' distance ran.
             */
            getActualDistance: function(distance) {
                return distance ? Math.round(distance * this.config.COEFFICIENT) : 0;
            },

            /**
             * Update the distance meter.
             * @param {number} distance
             * @param {number} deltaTime
             * @return {boolean} Whether the acheivement sound fx should be played.
             */
            update: function(deltaTime, distance) {
                var paint = true;
                var playSound = false;

                if (!this.achievement) {
                    distance = this.getActualDistance(distance);
                    // Score has gone beyond the initial digit count.
                    if (distance > this.maxScore && this.maxScoreUnits ==
                        this.config.MAX_DISTANCE_UNITS) {
                        this.maxScoreUnits++;
                        this.maxScore = parseInt(this.maxScore + '9');
                    } else {
                        this.distance = 0;
                    }

                    if (distance > 0) {
                        // Acheivement unlocked
                        if (distance % this.config.ACHIEVEMENT_DISTANCE == 0) {
                            // Flash score and play sound.
                            this.achievement = true;
                            this.flashTimer = 0;
                            playSound = true;
                        }

                        // Create a string representation of the distance with leading 0.
                        var distanceStr = (this.defaultString +
                            distance).substr(-this.maxScoreUnits);
                        this.digits = distanceStr.split('');
                    } else {
                        this.digits = this.defaultString.split('');
                    }
                } else {
                    // Control flashing of the score on reaching acheivement.
                    if (this.flashIterations <= this.config.FLASH_ITERATIONS) {
                        this.flashTimer += deltaTime;

                        if (this.flashTimer < this.config.FLASH_DURATION) {
                            paint = false;
                        } else if (this.flashTimer >
                            this.config.FLASH_DURATION * 2) {
                            this.flashTimer = 0;
                            this.flashIterations++;
                        }
                    } else {
                        this.achievement = false;
                        this.flashIterations = 0;
                        this.flashTimer = 0;
                    }
                }

                // Draw the digits if not flashing.
                if (paint) {
                    for (var i = this.digits.length - 1; i >= 0; i--) {
                        this.draw(i, parseInt(this.digits[i]));
                    }
                }

                this.drawHighScore();
                return playSound;
            },

            /**
             * Draw the high score.
             */
            drawHighScore: function() {
                this.canvasCtx.save();
                this.canvasCtx.globalAlpha = .8;
                for (var i = this.highScore.length - 1; i >= 0; i--) {
                    this.draw(i, parseInt(this.highScore[i], 10), true);
                }
                this.canvasCtx.restore();
            },

            /**
             * Set the highscore as a array string.
             * Position of char in the sprite: H - 10, I - 11.
             * @param {number} distance Distance ran in pixels.
             */
            setHighScore: function(distance) {
                distance = this.getActualDistance(distance);
                var highScoreStr = (this.defaultString +
                    distance).substr(-this.maxScoreUnits);

                this.highScore = ['10', '11', ''].concat(highScoreStr.split(''));
            },

            /**
             * Reset the distance meter back to '00000'.
             */
            reset: function() {
                this.update(0);
                this.achievement = false;
            }
        };


//******************************************************************************

        /**
         * Cloud background item.
         * Similar to an obstacle object but without collision boxes.
         * @param {HTMLCanvasElement} canvas Canvas element.
         * @param {Object} spritePos Position of image in sprite.
         * @param {number} containerWidth
         */
        function Cloud(canvas, spritePos, containerWidth) {
            this.canvas = canvas;
            this.canvasCtx = this.canvas.getContext('2d');
            this.spritePos = spritePos;
            this.containerWidth = containerWidth;
            this.xPos = containerWidth;
            this.yPos = 0;
            this.remove = false;
            this.cloudGap = getRandomNum(Cloud.config.MIN_CLOUD_GAP,
                Cloud.config.MAX_CLOUD_GAP);

            this.init();
        };


        /**
         * Cloud object config.
         * @enum {number}
         */
        Cloud.config = {
            HEIGHT: 14,
            MAX_CLOUD_GAP: 400,
            MAX_SKY_LEVEL: 30,
            MIN_CLOUD_GAP: 100,
            MIN_SKY_LEVEL: 71,
            WIDTH: 46
        };


        Cloud.prototype = {
            /**
             * Initialise the cloud. Sets the Cloud height.
             */
            init: function() {
                this.yPos = getRandomNum(Cloud.config.MAX_SKY_LEVEL,
                    Cloud.config.MIN_SKY_LEVEL);
                this.draw();
            },

            /**
             * Draw the cloud.
             */
            draw: function() {
                this.canvasCtx.save();
                var sourceWidth = Cloud.config.WIDTH;
                var sourceHeight = Cloud.config.HEIGHT;

                if (IS_HIDPI) {
                    sourceWidth = sourceWidth * 2;
                    sourceHeight = sourceHeight * 2;
                }

                this.canvasCtx.drawImage(Runner.imageSprite, this.spritePos.x,
                    this.spritePos.y,
                    sourceWidth, sourceHeight,
                    this.xPos, this.yPos,
                    Cloud.config.WIDTH, Cloud.config.HEIGHT);

                this.canvasCtx.restore();
            },

            /**
             * Update the cloud position.
             * @param {number} speed
             */
            update: function(speed) {
                if (!this.remove) {
                    this.xPos -= Math.ceil(speed);
                    this.draw();

                    // Mark as removeable if no longer in the canvas.
                    if (!this.isVisible()) {
                        this.remove = true;
                    }
                }
            },

            /**
             * Check if the cloud is visible on the stage.
             * @return {boolean}
             */
            isVisible: function() {
                return this.xPos + Cloud.config.WIDTH > 0;
            }
        };


//******************************************************************************

        /**
         * Nightmode shows a moon and stars on the horizon.
         */
        function NightMode(canvas, spritePos, containerWidth) {
            this.spritePos = spritePos;
            this.canvas = canvas;
            this.canvasCtx = canvas.getContext('2d');
            this.xPos = containerWidth - 50;
            this.yPos = 30;
            this.currentPhase = 0;
            this.opacity = 0;
            this.containerWidth = containerWidth;
            this.stars = [];
            this.drawStars = false;
            this.placeStars();
        };

        /**
         * @enum {number}
         */
        NightMode.config = {
            FADE_SPEED: 0.035,
            HEIGHT: 40,
            MOON_SPEED: 0.25,
            NUM_STARS: 2,
            STAR_SIZE: 9,
            STAR_SPEED: 0.3,
            STAR_MAX_Y: 70,
            WIDTH: 20
        };

        NightMode.phases = [140, 120, 100, 60, 40, 20, 0];

        NightMode.prototype = {
            /**
             * Update moving moon, changing phases.
             * @param {boolean} activated Whether night mode is activated.
             * @param {number} delta
             */
            update: function(activated, delta) {
                // Moon phase.
                if (activated && this.opacity == 0) {
                    this.currentPhase++;

                    if (this.currentPhase >= NightMode.phases.length) {
                        this.currentPhase = 0;
                    }
                }

                // Fade in / out.
                if (activated && (this.opacity < 1 || this.opacity == 0)) {
                    this.opacity += NightMode.config.FADE_SPEED;
                } else if (this.opacity > 0) {
                    this.opacity -= NightMode.config.FADE_SPEED;
                }

                // Set moon positioning.
                if (this.opacity > 0) {
                    this.xPos = this.updateXPos(this.xPos, NightMode.config.MOON_SPEED);

                    // Update stars.
                    if (this.drawStars) {
                        for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
                            this.stars[i].x = this.updateXPos(this.stars[i].x,
                                NightMode.config.STAR_SPEED);
                        }
                    }
                    this.draw();
                } else {
                    this.opacity = 0;
                    this.placeStars();
                }
                this.drawStars = true;
            },

            updateXPos: function(currentPos, speed) {
                if (currentPos < -NightMode.config.WIDTH) {
                    currentPos = this.containerWidth;
                } else {
                    currentPos -= speed;
                }
                return currentPos;
            },

            draw: function() {
                var moonSourceWidth = this.currentPhase == 3 ? NightMode.config.WIDTH * 2 :
                    NightMode.config.WIDTH;
                var moonSourceHeight = NightMode.config.HEIGHT;
                var moonSourceX = this.spritePos.x + NightMode.phases[this.currentPhase];
                var moonOutputWidth = moonSourceWidth;
                var starSize = NightMode.config.STAR_SIZE;
                var starSourceX = Runner.spriteDefinition.LDPI.STAR.x;

                if (IS_HIDPI) {
                    moonSourceWidth *= 2;
                    moonSourceHeight *= 2;
                    moonSourceX = this.spritePos.x +
                        (NightMode.phases[this.currentPhase] * 2);
                    starSize *= 2;
                    starSourceX = Runner.spriteDefinition.HDPI.STAR.x;
                }

                this.canvasCtx.save();
                this.canvasCtx.globalAlpha = this.opacity;

                // Stars.
                if (this.drawStars) {
                    for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
                        this.canvasCtx.drawImage(Runner.imageSprite,
                            starSourceX, this.stars[i].sourceY, starSize, starSize,
                            Math.round(this.stars[i].x), this.stars[i].y,
                            NightMode.config.STAR_SIZE, NightMode.config.STAR_SIZE);
                    }
                }

                // Moon.
                this.canvasCtx.drawImage(Runner.imageSprite, moonSourceX,
                    this.spritePos.y, moonSourceWidth, moonSourceHeight,
                    Math.round(this.xPos), this.yPos,
                    moonOutputWidth, NightMode.config.HEIGHT);

                this.canvasCtx.globalAlpha = 1;
                this.canvasCtx.restore();
            },

            // Do star placement.
            placeStars: function() {
                var segmentSize = Math.round(this.containerWidth /
                    NightMode.config.NUM_STARS);

                for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
                    this.stars[i] = {};
                    this.stars[i].x = getRandomNum(segmentSize * i, segmentSize * (i + 1));
                    this.stars[i].y = getRandomNum(0, NightMode.config.STAR_MAX_Y);

                    if (IS_HIDPI) {
                        this.stars[i].sourceY = Runner.spriteDefinition.HDPI.STAR.y +
                            NightMode.config.STAR_SIZE * 2 * i;
                    } else {
                        this.stars[i].sourceY = Runner.spriteDefinition.LDPI.STAR.y +
                            NightMode.config.STAR_SIZE * i;
                    }
                }
            },

            reset: function() {
                this.currentPhase = 0;
                this.opacity = 0;
                this.update(false);
            }

        };


//******************************************************************************

        /**
         * Horizon Line.
         * Consists of two connecting lines. Randomly assigns a flat / bumpy horizon.
         * @param {HTMLCanvasElement} canvas
         * @param {Object} spritePos Horizon position in sprite.
         * @constructor
         */
        function HorizonLine(canvas, spritePos) {
            this.spritePos = spritePos;
            this.canvas = canvas;
            this.canvasCtx = canvas.getContext('2d');
            this.sourceDimensions = {};
            this.dimensions = HorizonLine.dimensions;
            this.sourceXPos = [this.spritePos.x, this.spritePos.x +
            this.dimensions.WIDTH];
            this.xPos = [];
            this.yPos = 0;
            this.bumpThreshold = 0.5;

            this.setSourceDimensions();
            this.draw();
        };


        /**
         * Horizon line dimensions.
         * @enum {number}
         */
        HorizonLine.dimensions = {
            WIDTH: 600,
            HEIGHT: 12,
            YPOS: 127
        };


        HorizonLine.prototype = {
            /**
             * Set the source dimensions of the horizon line.
             */
            setSourceDimensions: function() {

                for (var dimension in HorizonLine.dimensions) {
                    if (IS_HIDPI) {
                        if (dimension != 'YPOS') {
                            this.sourceDimensions[dimension] =
                                HorizonLine.dimensions[dimension] * 2;
                        }
                    } else {
                        this.sourceDimensions[dimension] =
                            HorizonLine.dimensions[dimension];
                    }
                    this.dimensions[dimension] = HorizonLine.dimensions[dimension];
                }

                this.xPos = [0, HorizonLine.dimensions.WIDTH];
                this.yPos = HorizonLine.dimensions.YPOS;
            },

            /**
             * Return the crop x position of a type.
             */
            getRandomType: function() {
                return Math.random() > this.bumpThreshold ? this.dimensions.WIDTH : 0;
            },

            /**
             * Draw the horizon line.
             */
            draw: function() {
                this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[0],
                    this.spritePos.y,
                    this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
                    this.xPos[0], this.yPos,
                    this.dimensions.WIDTH, this.dimensions.HEIGHT);

                this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[1],
                    this.spritePos.y,
                    this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
                    this.xPos[1], this.yPos,
                    this.dimensions.WIDTH, this.dimensions.HEIGHT);
            },

            /**
             * Update the x position of an indivdual piece of the line.
             * @param {number} pos Line position.
             * @param {number} increment
             */
            updateXPos: function(pos, increment) {
                var line1 = pos;
                var line2 = pos == 0 ? 1 : 0;

                this.xPos[line1] -= increment;
                this.xPos[line2] = this.xPos[line1] + this.dimensions.WIDTH;

                if (this.xPos[line1] <= -this.dimensions.WIDTH) {
                    this.xPos[line1] += this.dimensions.WIDTH * 2;
                    this.xPos[line2] = this.xPos[line1] - this.dimensions.WIDTH;
                    this.sourceXPos[line1] = this.getRandomType() + this.spritePos.x;
                }
            },

            /**
             * Update the horizon line.
             * @param {number} deltaTime
             * @param {number} speed
             */
            update: function(deltaTime, speed) {
                var increment = Math.floor(speed * (FPS / 1000) * deltaTime);

                if (this.xPos[0] <= 0) {
                    this.updateXPos(0, increment);
                } else {
                    this.updateXPos(1, increment);
                }
                this.draw();
            },

            /**
             * Reset horizon to the starting position.
             */
            reset: function() {
                this.xPos[0] = 0;
                this.xPos[1] = HorizonLine.dimensions.WIDTH;
            }
        };


//******************************************************************************

        /**
         * Horizon background class.
         * @param {HTMLCanvasElement} canvas
         * @param {Object} spritePos Sprite positioning.
         * @param {Object} dimensions Canvas dimensions.
         * @param {number} gapCoefficient
         * @constructor
         */
        function Horizon(canvas, spritePos, dimensions, gapCoefficient) {
            this.canvas = canvas;
            this.canvasCtx = this.canvas.getContext('2d');
            this.config = Horizon.config;
            this.dimensions = dimensions;
            this.gapCoefficient = gapCoefficient;
            this.obstacles = [];
            this.obstacleHistory = [];
            this.horizonOffsets = [0, 0];
            this.cloudFrequency = this.config.CLOUD_FREQUENCY;
            this.spritePos = spritePos;
            this.nightMode = null;

            // Cloud
            this.clouds = [];
            this.cloudSpeed = this.config.BG_CLOUD_SPEED;

            // Horizon
            this.horizonLine = null;
            this.init();
        };


        /**
         * Horizon config.
         * @enum {number}
         */
        Horizon.config = {
            BG_CLOUD_SPEED: 0.2,
            BUMPY_THRESHOLD: .3,
            CLOUD_FREQUENCY: .5,
            HORIZON_HEIGHT: 16,
            MAX_CLOUDS: 6
        };


        Horizon.prototype = {
            /**
             * Initialise the horizon. Just add the line and a cloud. No obstacles.
             */
            init: function() {
                this.addCloud();
                this.horizonLine = new HorizonLine(this.canvas, this.spritePos.HORIZON);
                this.nightMode = new NightMode(this.canvas, this.spritePos.MOON,
                    this.dimensions.WIDTH);
            },

            /**
             * @param {number} deltaTime
             * @param {number} currentSpeed
             * @param {boolean} updateObstacles Used as an override to prevent
             *     the obstacles from being updated / added. This happens in the
             *     ease in section.
             * @param {boolean} showNightMode Night mode activated.
             */
            update: function(deltaTime, currentSpeed, updateObstacles, showNightMode) {
                this.runningTime += deltaTime;
                this.horizonLine.update(deltaTime, currentSpeed);
                this.nightMode.update(showNightMode);
                this.updateClouds(deltaTime, currentSpeed);

                if (updateObstacles) {
                    this.updateObstacles(deltaTime, currentSpeed);
                }
            },

            /**
             * Update the cloud positions.
             * @param {number} deltaTime
             * @param {number} currentSpeed
             */
            updateClouds: function(deltaTime, speed) {
                var cloudSpeed = this.cloudSpeed / 1000 * deltaTime * speed;
                var numClouds = this.clouds.length;

                if (numClouds) {
                    for (var i = numClouds - 1; i >= 0; i--) {
                        this.clouds[i].update(cloudSpeed);
                    }

                    var lastCloud = this.clouds[numClouds - 1];

                    // Check for adding a new cloud.
                    if (numClouds < this.config.MAX_CLOUDS &&
                        (this.dimensions.WIDTH - lastCloud.xPos) > lastCloud.cloudGap &&
                        this.cloudFrequency > Math.random()) {
                        this.addCloud();
                    }

                    // Remove expired clouds.
                    this.clouds = this.clouds.filter(function(obj) {
                        return !obj.remove;
                    });
                } else {
                    this.addCloud();
                }
            },

            /**
             * Update the obstacle positions.
             * @param {number} deltaTime
             * @param {number} currentSpeed
             */
            updateObstacles: function(deltaTime, currentSpeed) {
                // Obstacles, move to Horizon layer.
                var updatedObstacles = this.obstacles.slice(0);

                for (var i = 0; i < this.obstacles.length; i++) {
                    var obstacle = this.obstacles[i];
                    obstacle.update(deltaTime, currentSpeed);

                    // Clean up existing obstacles.
                    if (obstacle.remove) {
                        updatedObstacles.shift();
                    }
                }
                this.obstacles = updatedObstacles;

                if (this.obstacles.length > 0) {
                    var lastObstacle = this.obstacles[this.obstacles.length - 1];

                    if (lastObstacle && !lastObstacle.followingObstacleCreated &&
                        lastObstacle.isVisible() &&
                        (lastObstacle.xPos + lastObstacle.width + lastObstacle.gap) <
                        this.dimensions.WIDTH) {
                        this.addNewObstacle(currentSpeed);
                        lastObstacle.followingObstacleCreated = true;
                    }
                } else {
                    // Create new obstacles.
                    this.addNewObstacle(currentSpeed);
                }
            },

            removeFirstObstacle: function() {
                this.obstacles.shift();
            },

            /**
             * Add a new obstacle.
             * @param {number} currentSpeed
             */
            addNewObstacle: function(currentSpeed) {
                var obstacleTypeIndex = getRandomNum(0, Obstacle.types.length - 1);
                var obstacleType = Obstacle.types[obstacleTypeIndex];

                // Check for multiples of the same type of obstacle.
                // Also check obstacle is available at current speed.
                if (this.duplicateObstacleCheck(obstacleType.type) ||
                    currentSpeed < obstacleType.minSpeed) {
                    this.addNewObstacle(currentSpeed);
                } else {
                    var obstacleSpritePos = this.spritePos[obstacleType.type];

                    this.obstacles.push(new Obstacle(this.canvasCtx, obstacleType,
                        obstacleSpritePos, this.dimensions,
                        this.gapCoefficient, currentSpeed, obstacleType.width));

                    this.obstacleHistory.unshift(obstacleType.type);

                    if (this.obstacleHistory.length > 1) {
                        this.obstacleHistory.splice(Runner.config.MAX_OBSTACLE_DUPLICATION);
                    }
                }
            },

            /**
             * Returns whether the previous two obstacles are the same as the next one.
             * Maximum duplication is set in config value MAX_OBSTACLE_DUPLICATION.
             * @return {boolean}
             */
            duplicateObstacleCheck: function(nextObstacleType) {
                var duplicateCount = 0;

                for (var i = 0; i < this.obstacleHistory.length; i++) {
                    duplicateCount = this.obstacleHistory[i] == nextObstacleType ?
                        duplicateCount + 1 : 0;
                }
                return duplicateCount >= Runner.config.MAX_OBSTACLE_DUPLICATION;
            },

            /**
             * Reset the horizon layer.
             * Remove existing obstacles and reposition the horizon line.
             */
            reset: function() {
                this.obstacles = [];
                this.horizonLine.reset();
                this.nightMode.reset();
            },

            /**
             * Update the canvas width and scaling.
             * @param {number} width Canvas width.
             * @param {number} height Canvas height.
             */
            resize: function(width, height) {
                this.canvas.width = width;
                this.canvas.height = height;
            },

            /**
             * Add a new cloud to the horizon.
             */
            addCloud: function() {
                this.clouds.push(new Cloud(this.canvas, this.spritePos.CLOUD,
                    this.dimensions.WIDTH));
            }
        };
    })();
    </script>
</head>
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        </div>
        <button id="details-button" class="text-button small-link singular" onclick="detailsButtonClick(); toggleHelpBox()" jscontent="details" jsdisplay="(suggestionsDetails &amp;&amp; suggestionsDetails.length &gt; 0) || diagnose" jsvalues=".detailsText:details; .hideDetailsText:hideDetails;" jstcache="3" style="display: none;"></button>
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</div>


<script jstcache="0">// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview This file defines a singleton which provides access to all data
 * that is available as soon as the page's resources are loaded (before DOM
 * content has finished loading). This data includes both localized strings and
 * any data that is important to have ready from a very early stage (e.g. things
 * that must be displayed right away).
 *
 * Note that loadTimeData is not guaranteed to be consistent between page
 * refreshes (https://crbug.com/740629) and should not contain values that might
 * change if the page is re-opened later.
 */

/**
 * @typedef {{
 *   substitutions: (Array<string>|undefined),
 *   attrs: (Object<function(Node, string):boolean>|undefined),
 *   tags: (Array<string>|undefined),
 * }}
 */
var SanitizeInnerHtmlOpts;

/** @type {!LoadTimeData} */ var loadTimeData;

// Expose this type globally as a temporary work around until
// https://github.com/google/closure-compiler/issues/544 is fixed.
/** @constructor */
function LoadTimeData(){}

(function() {
    'use strict';

    LoadTimeData.prototype = {
        /**
         * Sets the backing object.
         *
         * Note that there is no getter for |data_| to discourage abuse of the form:
         *
         *     var value = loadTimeData.data()['key'];
         *
         * @param {Object} value The de-serialized page data.
         */
        set data(value) {
            expect(!this.data_, 'Re-setting data.');
            this.data_ = value;
        },

        /**
         * Returns a JsEvalContext for |data_|.
         * @returns {JsEvalContext}
         */
        createJsEvalContext: function() {
            return new JsEvalContext(this.data_);
        },

        /**
         * @param {string} id An ID of a value that might exist.
         * @return {boolean} True if |id| is a key in the dictionary.
         */
        valueExists: function(id) {
            return id in this.data_;
        },

        /**
         * Fetches a value, expecting that it exists.
         * @param {string} id The key that identifies the desired value.
         * @return {*} The corresponding value.
         */
        getValue: function(id) {
            expect(this.data_, 'No data. Did you remember to include strings.js?');
            var value = this.data_[id];
            expect(typeof value != 'undefined', 'Could not find value for ' + id);
            return value;
        },

        /**
         * As above, but also makes sure that the value is a string.
         * @param {string} id The key that identifies the desired string.
         * @return {string} The corresponding string value.
         */
        getString: function(id) {
            var value = this.getValue(id);
            expectIsType(id, value, 'string');
            return /** @type {string} */ (value);
        },

        /**
         * Returns a formatted localized string where $1 to $9 are replaced by the
         * second to the tenth argument.
         * @param {string} id The ID of the string we want.
         * @param {...(string|number)} var_args The extra values to include in the
         *     formatted output.
         * @return {string} The formatted string.
         */
        getStringF: function(id, var_args) {
            var value = this.getString(id);
            if (!value)
                return '';

            var args = Array.prototype.slice.call(arguments);
            args[0] = value;
            return this.substituteString.apply(this, args);
        },

        /**
         * Make a string safe for use with with Polymer bindings that are
         * inner-h-t-m-l (or other innerHTML use).
         * @param {string} rawString The unsanitized string.
         * @param {SanitizeInnerHtmlOpts=} opts Optional additional allowed tags and
         *     attributes.
         * @return {string}
         */
        sanitizeInnerHtml: function(rawString, opts) {
            opts = opts || {};
            return parseHtmlSubset('<b>' + rawString + '</b>', opts.tags, opts.attrs)
                .firstChild.innerHTML;
        },

        /**
         * Returns a formatted localized string where $1 to $9 are replaced by the
         * second to the tenth argument. Any standalone $ signs must be escaped as
         * $$.
         * @param {string} label The label to substitute through.
         *     This is not an resource ID.
         * @param {...(string|number)} var_args The extra values to include in the
         *     formatted output.
         * @return {string} The formatted string.
         */
        substituteString: function(label, var_args) {
            var varArgs = arguments;
            return label.replace(/\$(.|$|\n)/g, function(m) {
                assert(m.match(/\$[$1-9]/), 'Unescaped $ found in localized string.');
                return m == '$$' ? '$' : varArgs[m[1]];
            });
        },

        /**
         * Returns a formatted string where $1 to $9 are replaced by the second to
         * tenth argument, split apart into a list of pieces describing how the
         * substitution was performed. Any standalone $ signs must be escaped as $$.
         * @param {string} label A localized string to substitute through.
         *     This is not an resource ID.
         * @param {...(string|number)} var_args The extra values to include in the
         *     formatted output.
         * @return {!Array<!{value: string, arg: (null|string)}>} The formatted
         *     string pieces.
         */
        getSubstitutedStringPieces: function(label, var_args) {
            var varArgs = arguments;
            // Split the string by separately matching all occurrences of $1-9 and of
            // non $1-9 pieces.
            var pieces = (label.match(/(\$[1-9])|(([^$]|\$([^1-9]|$))+)/g) ||
                []).map(function(p) {
                // Pieces that are not $1-9 should be returned after replacing $$
                // with $.
                if (!p.match(/^\$[1-9]$/)) {
                    assert(
                        (p.match(/\$/g) || []).length % 2 == 0,
                        'Unescaped $ found in localized string.');
                    return {value: p.replace(/\$\$/g, '$'), arg: null};
                }

                // Otherwise, return the substitution value.
                return {value: varArgs[p[1]], arg: p};
            });

            return pieces;
        },

        /**
         * As above, but also makes sure that the value is a boolean.
         * @param {string} id The key that identifies the desired boolean.
         * @return {boolean} The corresponding boolean value.
         */
        getBoolean: function(id) {
            var value = this.getValue(id);
            expectIsType(id, value, 'boolean');
            return /** @type {boolean} */ (value);
        },

        /**
         * As above, but also makes sure that the value is an integer.
         * @param {string} id The key that identifies the desired number.
         * @return {number} The corresponding number value.
         */
        getInteger: function(id) {
            var value = this.getValue(id);
            expectIsType(id, value, 'number');
            expect(value == Math.floor(value), 'Number isn\'t integer: ' + value);
            return /** @type {number} */ (value);
        },

        /**
         * Override values in loadTimeData with the values found in |replacements|.
         * @param {Object} replacements The dictionary object of keys to replace.
         */
        overrideValues: function(replacements) {
            expect(
                typeof replacements == 'object',
                'Replacements must be a dictionary object.');
            for (var key in replacements) {
                this.data_[key] = replacements[key];
            }
        }
    };

    /**
     * Checks condition, displays error message if expectation fails.
     * @param {*} condition The condition to check for truthiness.
     * @param {string} message The message to display if the check fails.
     */
    function expect(condition, message) {
        if (!condition) {
            console.error(
                'Unexpected condition on ' + document.location.href + ': ' + message);
        }
    }

    /**
     * Checks that the given value has the given type.
     * @param {string} id The id of the value (only used for error message).
     * @param {*} value The value to check the type on.
     * @param {string} type The type we expect |value| to be.
     */
    function expectIsType(id, value, type) {
        expect(
            typeof value == type, '[' + value + '] (' + id + ') is not a ' + type);
    }

    expect(!loadTimeData, 'should only include this file once');
    loadTimeData = new LoadTimeData;
})();
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Note: vulcanize sometimes disables GRIT processing. If you're importing i18n
// stuff with <link rel="import">, you should probably be using
// html/i18n_template.html instead of this file.

// // Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/** @typedef {Document|DocumentFragment|Element} */
var ProcessingRoot;

/**
 * @fileoverview This is a simple template engine inspired by JsTemplates
 * optimized for i18n.
 *
 * It currently supports three handlers:
 *
 *   * i18n-content which sets the textContent of the element.
 *
 *     <span i18n-content="myContent"></span>
 *
 *   * i18n-options which generates <option> elements for a <select>.
 *
 *     <select i18n-options="myOptionList"></select>
 *
 *   * i18n-values is a list of attribute-value or property-value pairs.
 *     Properties are prefixed with a '.' and can contain nested properties.
 *
 *     <span i18n-values="title:myTitle;.style.fontSize:fontSize"></span>
 *
 * This file is a copy of i18n_template.js, with minor tweaks to support using
 * load_time_data.js. It should replace i18n_template.js eventually.
 */

var i18nTemplate = (function() {
    /**
     * This provides the handlers for the templating engine. The key is used as
     * the attribute name and the value is the function that gets called for every
     * single node that has this attribute.
     * @type {!Object}
     */
    var handlers = {
        /**
         * This handler sets the textContent of the element.
         * @param {!HTMLElement} element The node to modify.
         * @param {string} key The name of the value in |data|.
         * @param {!LoadTimeData} data The data source to draw from.
         * @param {!Set<ProcessingRoot>} visited
         */
        'i18n-content': function(element, key, data, visited) {
            element.textContent = data.getString(key);
        },

        /**
         * This handler adds options to a <select> element.
         * @param {!HTMLElement} select The node to modify.
         * @param {string} key The name of the value in |data|. It should
         *     identify an array of values to initialize an <option>. Each value,
         *     if a pair, represents [content, value]. Otherwise, it should be a
         *     content string with no value.
         * @param {!LoadTimeData} data The data source to draw from.
         * @param {!Set<ProcessingRoot>} visited
         */
        'i18n-options': function(select, key, data, visited) {
            var options = data.getValue(key);
            options.forEach(function(optionData) {
                var option = typeof optionData == 'string' ?
                    new Option(optionData) :
                    new Option(optionData[1], optionData[0]);
                select.appendChild(option);
            });
        },

        /**
         * This is used to set HTML attributes and DOM properties. The syntax is:
         *   attributename:key;
         *   .domProperty:key;
         *   .nested.dom.property:key
         * @param {!HTMLElement} element The node to modify.
         * @param {string} attributeAndKeys The path of the attribute to modify
         *     followed by a colon, and the name of the value in |data|.
         *     Multiple attribute/key pairs may be separated by semicolons.
         * @param {!LoadTimeData} data The data source to draw from.
         * @param {!Set<ProcessingRoot>} visited
         */
        'i18n-values': function(element, attributeAndKeys, data, visited) {
            var parts = attributeAndKeys.replace(/\s/g, '').split(/;/);
            parts.forEach(function(part) {
                if (!part)
                    return;

                var attributeAndKeyPair = part.match(/^([^:]+):(.+)$/);
                if (!attributeAndKeyPair)
                    throw new Error('malformed i18n-values: ' + attributeAndKeys);

                var propName = attributeAndKeyPair[1];
                var propExpr = attributeAndKeyPair[2];

                var value = data.getValue(propExpr);

                // Allow a property of the form '.foo.bar' to assign a value into
                // element.foo.bar.
                if (propName[0] == '.') {
                    var path = propName.slice(1).split('.');
                    var targetObject = element;
                    while (targetObject && path.length > 1) {
                        targetObject = targetObject[path.shift()];
                    }
                    if (targetObject) {
                        targetObject[path] = value;
                        // In case we set innerHTML (ignoring others) we need to recursively
                        // check the content.
                        if (path == 'innerHTML') {
                            for (var i = 0; i < element.children.length; ++i) {
                                processWithoutCycles(element.children[i], data, visited, false);
                            }
                        }
                    }
                } else {
                    element.setAttribute(propName, /** @type {string} */ (value));
                }
            });
        }
    };

    var prefixes = [''];

    // Only look through shadow DOM when it's supported. As of April 2015, iOS
    // Chrome doesn't support shadow DOM.
    if (Element.prototype.createShadowRoot)
        prefixes.push('* /deep/ ');

    var attributeNames = Object.keys(handlers);
    var selector = prefixes
        .map(function(prefix) {
            return prefix + '[' +
                attributeNames.join('], ' + prefix + '[') + ']';
        })
        .join(', ');

    /**
     * Processes a DOM tree using a |data| source to populate template values.
     * @param {!ProcessingRoot} root The root of the DOM tree to process.
     * @param {!LoadTimeData} data The data to draw from.
     */
    function process(root, data) {
        processWithoutCycles(root, data, new Set(), true);
    }

    /**
     * Internal process() method that stops cycles while processing.
     * @param {!ProcessingRoot} root
     * @param {!LoadTimeData} data
     * @param {!Set<ProcessingRoot>} visited Already visited roots.
     * @param {boolean} mark Whether nodes should be marked processed.
     */
    function processWithoutCycles(root, data, visited, mark) {
        if (visited.has(root)) {
            // Found a cycle. Stop it.
            return;
        }

        // Mark the node as visited before recursing.
        visited.add(root);

        var importLinks = root.querySelectorAll('link[rel=import]');
        for (var i = 0; i < importLinks.length; ++i) {
            var importLink = /** @type {!HTMLLinkElement} */ (importLinks[i]);
            if (!importLink.import) {
                // Happens when a <link rel=import> is inside a <template>.
                // TODO(dbeam): should we log an error if we detect that here?
                continue;
            }
            processWithoutCycles(importLink.import, data, visited, mark);
        }

        var templates = root.querySelectorAll('template');
        for (var i = 0; i < templates.length; ++i) {
            var template = /** @type {HTMLTemplateElement} */ (templates[i]);
            if (!template.content)
                continue;
            processWithoutCycles(template.content, data, visited, mark);
        }

        var isElement = root instanceof Element;
        if (isElement && root.webkitMatchesSelector(selector))
            processElement(/** @type {!Element} */ (root), data, visited);

        var elements = root.querySelectorAll(selector);
        for (var i = 0; i < elements.length; ++i) {
            processElement(elements[i], data, visited);
        }

        if (mark) {
            var processed = isElement ? [root] : root.children;
            if (processed) {
                for (var i = 0; i < processed.length; ++i) {
                    processed[i].setAttribute('i18n-processed', '');
                }
            }
        }
    }

    /**
     * Run through various [i18n-*] attributes and populate.
     * @param {!Element} element
     * @param {!LoadTimeData} data
     * @param {!Set<ProcessingRoot>} visited
     */
    function processElement(element, data, visited) {
        for (var i = 0; i < attributeNames.length; i++) {
            var name = attributeNames[i];
            var attribute = element.getAttribute(name);
            if (attribute != null)
                handlers[name](element, attribute, data, visited);
        }
    }

    return {process: process};
}());

// // Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

i18nTemplate.process(document, loadTimeData);

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